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How To Calculate Standard Deviation

Updated on December 04, 2006

First, you need to determine the mean. The mean of a list of numbers is the sum of those numbers divided by the quantity of items in the list (read: add all the numbers up and divide by how many there are).

Then, subtract the mean from every number to get the list of deviations. Create a list of these numbers. It's OK to get negative numbers here. Next, square the resulting list of numbers (read: multiply them with themselves).

Add up all of the resulting squares to get their total sum. Divide your result by one less than the number of items in the list.

To get the standard deviation, just take the square root of the resulting number

I know this sounds confusing, but just check out this example:

your list of numbers: 1, 3, 4, 6, 9, 19

mean: (1+3+4+6+9+19) / 6 = 42 / 6 = 7

list of deviations: -6, -4, -3, -1, 2, 12

squares of deviations: 36, 16, 9, 1, 4, 144

sum of deviations: 36+16+9+1+4+144 = 210

divided by one less than the number of items in the list: 210 / 5 = 42

square root of this number: square root (42) = about 6.48

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    • Paul Edmondson profile image

      Paul Edmondson 10 years ago from Burlingame, CA

      Nice example. Very easy to understand.

    • profile image

      Ole 10 years ago

      Yes, exept: you say that you will subtract the mean from every number which in your example is 7, but you subtract the number 6 from every number to get the list of deviations? it is the mean and not the amount of numbers in the list that should be used right?

    • profile image

      Wilson  10 years ago

      It's quite easy and straightforward. Thanks for refreshing my highschool Maths. I am currently preparing for GMAT exams and i definitely need this review.

    • profile image

      Wilson  10 years ago

      I am still the Wilson above. Yes Ole you definitely are right. The mean is 7, so we have to subtract the mean from every number. I am sorry i didn't see that. But generally the procedure is easy and straightforward.

    • profile image
      Author

      sonia 10 years ago

      Sorry about that oversight - it's corrected now! Thanks for pointing it out.

    • profile image

      MaryAnn 10 years ago

      I'm trying to pass a stats class to get into a Masters program and this is the only thing that's made any sense so far--THANKS!!!

    • profile image

      Amani 10 years ago

      Thank you very much... it helped me in performing the calculations of my experiment in this very critical time…!! J

    • profile image

      Lex 9 years ago

      Thanks! I learned something new!

    • profile image

      Ron 9 years ago

      Wow! That was new for me!

    • profile image

      Adam 9 years ago

      Great post! That's what I needed!

    • profile image

      Gabe 9 years ago

      Nice post! It really helped me!

    • profile image

      michelle 9 years ago

      Thank you very much for the nice, straightforward info on standard deviations, it totally helped my daughter!

    • thecounterpunch profile image

      thecounterpunch 9 years ago

      Do not learn without understanding :)

      https://hubpages.com/money/Normal_Law

    • profile image

      dajoo 9 years ago

      good way to explain

    • profile image

      Sophie 9 years ago

      Awsome example and walkthrough of SD... it really helped me a lot

      Thanks

    • profile image

      Dharam 9 years ago

      thanks sonia, you removed my very big confusion by giving live example

      thanks once again

    • profile image

      john 9 years ago

      thanks so much!

    • profile image

      AS 9 years ago

      Okay, now how do I understand the numbers once I have calculated the standard deviation. Can you provide some examples?

    • profile image

      Col 9 years ago

      So helpful, thank you. You have succeeded where my Quants professor failed - to explain this in plain language. You don't fancy having a go at Variance for me do you?????

      Am really struggling and have an exam next week.

    • profile image

      wilfred 9 years ago

      hello

    • profile image

      isaac 9 years ago

      thanks a lot i m having a final exam within 2 days

    • profile image

      misho 9 years ago

      awesome, thanks!

    • profile image

      Linda 9 years ago

      Amazing stuff...thanks

    • profile image

      Naaman Kipumbu 9 years ago

      Great refreshment for me. I'm studying Computer Science and Information Processing with ABMA, UK. Great deal a job!

    • profile image

      Trey 9 years ago

      Was easier then everything I learned in Stats :-)

    • profile image

      Ankur 9 years ago

      That's exactly what I was looking for......good work

    • profile image

      Ankur 9 years ago

      That's exactly what I was looking for......good work

    • reash profile image

      reash 9 years ago

      Hi

      Great hub..Way back in college I was having a hard time figuring out numbers but I managed to find a way though. You must be very good in numbers.

    • profile image

      Aaron 9 years ago

      right on....i like this site

    • profile image

      Kassemi 9 years ago

      thanks very much sonia ur very easy

      I will use it in building a C# program

    • profile image

      Aruna 9 years ago

      Thanx for giving me apt solution.

    • profile image

      Aruna 9 years ago

      X

      d = X- Mean

      d2 = d x d

      1

      (1-7)= -6

      36

      3

      (3-7) = -4

      16

      4

      (4-7) = -3

      9

      6

      (6-7) = -1

      1

      9

      (9-7) = 2

      4

      19

      (19-7) = 12

      144

      Mean = ∑x/n = Sum(1+3+4+6+9+19)/6 = 42/6 = 7

      Therefore Standard Deviation = ∑d2 / (n-1) = (36+16+9+1+4+144)/ (6-1)

      = 210/5

      = 42

      So, Standard Deviation = √42 = 6.48

      As per sonia example i have presented with formula & table for exam point of view

    • profile image

      Pat 9 years ago

    • profile image

      applepie 9 years ago

      Aruna, you made it look so simple!!!! I'm sure it is but I am currently in a stats course and having a difficult time making sense of it all, do you have any suggestions where I can get some online help with understanding how to work problems out....thx.

    • profile image

      Catherine 9 years ago

      The only thing that the example is missing is the following: you haven't articulated where you are testing a sample or a population. If you are testing a sample, then n would be the denominator. However if you are testing a population, you will need to divide by n-1.

    • profile image

      sam 9 years ago

      does anyone know how to use spss? and do uni level stats stuff??

    • profile image

      math penguin 9 years ago

      Yes, Sam I am familiar with SPSS. What can I do for you

    • profile image

      Chung 9 years ago

      yes that's an EASY example, but how do u calculate the standard deviation when there is 20 values and each one is like 5 digits with decimals? it will take like over 10 minutes by hand and for an exam that is way to long for a stdev question. Also, how do u know when to find the population standard deviation or the sample standard deviation?

    • profile image

      Lazuardi 9 years ago

      thanks a lot! really help me

    • profile image

      hannah 9 years ago

      that was excellent, very helpful, allowing me to complete my assignment due tomorrow with a little less stress! thumbs up, very appreicative!

    • profile image

      Herbert  9 years ago

      A bit confused up there about the argument by Ole. What is it? Divide by 6 or 7? The 6 is the number of observations while the 7 is the mean! Can someone help there?

    • profile image

      simone 9 years ago

      uber helpful...thanks!

    • profile image

      Celine 9 years ago

      I get the jist of standard deviation but what doees the number at the end show??

      (am doing some maths statistic coursework at the moment)

      thanks

    • profile image

      buddy_eagle 9 years ago

      thxs... a lot for posting this.... it was a gr8 help

    • profile image

      Mikhaila 9 years ago

      Thank you so much! I am doing an online course on statistics and this has really helped me.

    • profile image

      SXE Chris 9 years ago

      thanka a bundle! I had to do an assignment for an anthropology course I am taking at university and this helped me tremendously!! Thanks again, so much!

    • profile image

      ISuckAtMath 9 years ago

      YA im like doing my homework and i like don't get any of this crap I'm only in like 7th grade... But whatevs, I just wanted to say--OMG UGLY BETTY is on!!!!!!! sry gtg BIBI!!

    • profile image

      Celine 9 years ago

      What does the final number show? and what can I do with it.. I'm apparently meant to use it to help support my hypothesis that height follows a normal distribution in a school..

    • profile image

      Kaitlyn Giammatteo 9 years ago

      You made it very easy...thank you!

    • profile image

      kashmere 9 years ago

      thanks it really helped a quick reference............

    • profile image

      rani 9 years ago

      what is it with all the fit asian boys

    • profile image

      rani 9 years ago

      a wanna take 1 home

    • profile image

      rani 9 years ago

      i'll be rameshes friend

      how do you do it in india

      can't wait to ring your bell

      god............. ramesh your mathes turns me on babyXXX

    • profile image

      gagan sharma 9 years ago

      thanx a lot lot Sonia....i just forgot how 2 calculate it...u helped me learning it again..great work..

    • profile image

      aaron 9 years ago

      thank you,quick method

    • profile image

      aaron 9 years ago

      thank you,quick method

    • profile image

      adeel 9 years ago

      gr8 example

    • profile image

      imran 9 years ago

      Good- A very easy way to understand standard deviation

    • profile image

      sara 9 years ago

      bless ya..it had been very useful in answering ma assignment..

      loads of thanks:)

    • profile image

      Jolene 9 years ago

      Thank you soo much!

      This helped me out a lot.

    • profile image

      AJ 9 years ago

      wow, thank you so much! i had been trying for hours to understand the stupid book but your explanation was really easy to understand! great work!

    • profile image

      Nontembiso 9 years ago

      Thank yo so much Sonia, now I can see the way through my Masters results.

    • profile image

      Nontembiso 9 years ago

      Thank yo so much Sonia, now I can see the way through my Masters results.

    • profile image

      the best 9 years ago

      thanks for the great post!

    • profile image

      Ash 9 years ago

      You've written sum of deviations when it should be sum of squares of deviations...

    • profile image

      Neil 9 years ago

      Sonia, arent´t you suppose to divide by the number of samples? Why did you substrate 1 from it?

    • profile image

      Brian 9 years ago

      This is wrong, you don't divide by (n-1), you divide by n.

    • profile image

      Pheonix 9 years ago

      Thanx very much..... it really simplified everything. thanx again

    • profile image

      DC 9 years ago

      ITS WRONG.... the Standard Deviation is actually 5.916

    • profile image

      BandKid 8 years ago

      No, DC, you are wrong...you found the population standard deviation

    • profile image

      Davaine 8 years ago

      thnx a lot sonia it reeeeeli helpd me undestand sd... it wuz crucial 4 mii coursework

    • profile image

      cagney 8 years ago

      thank you so much

    • profile image

      Kristie 8 years ago

      why don't u just say that the standrad deviation is the root of the mean?

    • profile image

      Terri  8 years ago

      Thanks! Simplying the steps has really increased my understanding!

    • profile image

      CTL 8 years ago

      :)

      Nice n' Easy!

    • profile image

      Marri 8 years ago

      Great example

    • profile image

      Hiba 8 years ago

      Thank you very much . it really helped me a lot!!

    • profile image

      Rob 8 years ago

      far out, people love ya ..... But it is an excellent, easy to follow example.

      The hardest thing about it is trying to figure out what the x and n etc all represent... this example fills in the pieces of the puzzle. Cheers

    • profile image

      Suzanne 8 years ago

      Thank you soooo much, this has really helped me out, I was at the end of my tether until my tutor recommeded this sight. A few more practise's and I'll be there, I hope! :-)

    • profile image

      Bea 8 years ago

      Thank you very much for taking the time to explain this in plain English. I am taking my Masters Program and it has been a while since I took statistics as an undergrad.

    • profile image

      Marques R. Wilson 8 years ago

      I took Stat years ago, the answer here is simpler and I think I can remember and program it. :)

    • profile image

      helen udoewah 8 years ago

      this has made me a better mathematician i think i will pass my degress stats without tears thinks guys.

    • profile image

      jerry 8 years ago

      excellent . That was great

    • profile image

      Ale 8 years ago

      Thank you so much, this really really helped!

    • profile image

      venkatesh 8 years ago

      Thank you so much, this really really helped!

    • profile image

      Peter 8 years ago

      Thanks Sonia,

      Very informative easy to understand and follow format!

    • profile image

      Crossy 8 years ago

      Or just use a calculator in stat x mode.

    • profile image

      seema 8 years ago

      thank you

      thats nice explanation with example

    • profile image

      Brian 8 years ago

      My GMAT study book has a different method for calculating standard dev. Why do you divide by 1 less the number of items in the list in the last step? As far as I've seen everywhere else, this is incorrect. According to my GMAT study book you calculate the mean of the squares you computed in step 2, and the square root the mean.

    • profile image

      MAVERICK 8 years ago

      GOD BLESS YOUR SOUL!

    • profile image

      ChemQueen 8 years ago

      Super super helpful!

    • profile image

      vineyl oberoi 8 years ago

      thank you very sonia u helped a lot

    • profile image

      joanne 8 years ago

      Very helpful.....Thanks!!!

    • profile image

      DC 8 years ago

      Very! Very! helpful

    • profile image

      Alyssa 8 years ago

      Anyone knoq hoiw to graph it????

    • profile image

      mike 8 years ago

      this helped a lot. looks like i won't fail my test today!

    • profile image

      dizzee 8 years ago

      thnk youu really helped!

    • profile image

      dizzee 8 years ago

      thnk youu really helped!

    • profile image

      Warren 8 years ago

      I'm still confused

      But this is better then my statistics formulas i was given, looks like i'm doing it the long way.

    • profile image

      Joe 8 years ago

      that was very easy to understand..

      thank you

    • profile image

      Naungsai 8 years ago

      SD is a dreadful tem for me before. Now I understand it clearly.

      Willing to see more simple examples of others teams of Statistic like this.

    • profile image

      megaman 8 years ago

      wow it acctulayy helpped.. thx alot

      great example

    • profile image

      Judas mesias 8 years ago

      man this helpd wid my coursework

      thnx we owe u one

    • profile image

      Judy Martin 8 years ago

      Simplified and quite easy to understand!.... where is my lecturer!

    • profile image

      Mike 8 years ago

      There are two version

      Using n-1 or just using n

      If you have a large population you can use n, but for small samples like this you will use n-1..

    • profile image

      Kathy 8 years ago

      Standard Deviation always confused me this helped a lot.

    • profile image

      neel 8 years ago

      omg thank you so much. i have this sub who can't teach right and the regular teacher is in chemotheraphy. basically there are no As in the class and very few Bs and im lucky to have a B in it. online helps a lot. thank you

    • profile image

      surendra 8 years ago

      i have a sirvey in which 1 person choose apple, 2 persons choose bananas, 7 persons choose oranges and 3 persons choose mango. (total 13 persons). i got the standard deviation as 0.862 (from a survey system) and standard error as 0.239.

      could some one explain me of how the standard deviation came as 0.862 .

    • profile image

      KRISB 8 years ago

      THANKS!

    • profile image

      Steve 8 years ago

      Excellent quickie refresher, thanks a lot

    • profile image

      tania 8 years ago

      man this is such a help..

      thanks man...i really really needed it for

      ma hwk...

    • profile image

      Jay 8 years ago

      Simply Awesome

    • profile image

      frank 8 years ago

      Awesome. thanks a bunch

    • profile image

      Kirill 8 years ago

      What if the initial list has negative numbers. For example,

      1, -3, 4, 6, 9, 19. Does the answer change and if so, what are the rules? Thanks!

    • profile image

      HateMaths 8 years ago

      Just to put it out there for any confused people(the only thing Sonia missed out) - when you square the numbers, the minus sign disappears and the result should be a positive number.

      Amazingly simple method by the way, even I was able to follow. Thanks a lot =)

    • profile image

      Stephanie 8 years ago

      Awesome example!!! You scared me at first but once the numbers were there it all made sense....thank you much!!

    • profile image

      Kevin 8 years ago

      I have a 600 Lvl QDM class and this was is a great refreasher! My text book made it more complicated then it had to be. Great Job! Whew~!

    • profile image

      nicole 8 years ago

      i still don't understand..do you have to make a table or what??

      im only in fourth year at school and have my prelims in 3 weeks and im very nervous

      i don't get anything to do with standard deviation, means and factorising

      my numbers im working on are 45pence 54 pence 59pence 61pence 71pence

      i know the mean is 58pence but i dont get the next bit its asking me to do

      please help i need it badly

      thankyou

      nicolee

      x

    • profile image

      nicole(again) 8 years ago

      the way i think i was taught was with a table:S and the middle table added up to 0 or something, i cant find my jotter for it though

      if you have time and get round to doing my little sum would the answer be 364?

      nicole

      x

    • profile image

      Warren 8 years ago

      Nicole, I will try my best to do your question

      Mean: (45 + 54 + 59 + 61 +71) / 5 = 290/5 = 58 Pence

      List of Deviations: -13, -4, +1, +3, +13

      (List of Deviations is The Mean minus each value (i.e 58 is the mean, so minus 48 pence)

      squares of deviations: 169 + 16 + 1 + 9 + 169

      Sum of Deviations = 169 + 16+ 1 + 9 +169 = 364

      364 is NOT the final answer though...

      divided by one less than the number of items in the list: 364 / 4 = 91

      ('one less' is referring to the mean - 1...so 5-1 = 4)

      quare root of this number: square root (91) = Which is approx. 9.54

      So 9.54 is the standard deviation.

      Hopefully that helps.. It helped me to make sure I understand it for my exam tomorrow lol.

    • profile image

      kc 8 years ago

      the minus one is known as degrees of freedom

    • profile image

      martha 8 years ago

      hi could anyone help me please I have this big assigment and I really do not understand anything

      <!-- /* Style Definitions */ p.MsoNormal, li.MsoNormal, div.MsoNormal {mso-style-parent:""; margin:0in; margin-bottom:.0001pt; mso-pagination:widow-orphan; font-size:12.0pt; font-family:"Times New Roman"; mso-fareast-font-family:"Times New Roman";} @page Section1 {size:8.5in 11.0in; margin:1.0in 1.25in 1.0in 1.25in; mso-header-margin:.5in; mso-footer-margin:.5in; mso-paper-source:0;} div.Section1 {page:Section1;} /* List Definitions */ @list l0 {mso-list-id:1162313390; mso-list-type:hybrid; mso-list-template-ids:1248870110 67698703 67698713 67698715 67698703 67698713 67698715 67698703 67698713 67698715;} @list l0:level1 {mso-level-tab-stop:.5in; mso-level-number-position:left; text-indent:-.25in;} ol {margin-bottom:0in;} ul {margin-bottom:0in;} -->

      Par, Inc., is a major manufacturer of golf equipment. Management believes that Par’s market share could be increased with the introduction of a cut-resistant, longer-lasting golf ball. Therefore, the research group at Par has been investigating a new golf ball coating designed to resist cuts a provide a more durable ball. The tests with the coating have been promising.

      One of the researchers voiced concern about the effect of the new coating on driving distances. Par would like the new cut-resistant ball to offer driving distances comparable to those of the current-model golf ball. To compare the driving distances for the two balls, 40 balls of both the new and current models were subject distance tests. The testing was performed with a mechanical hitting machine so that any difference between the mean distances for the two models could be attributed to a difference in the two models. The results of the tests, with distances measured to the nearest yard, are on the next page. A file with this data is also available on blackboard, use it so you do not need to reenter all the samples.

      Assignment:

      Managerial Report

      Formulate and present the rationale for a hypothesis test that Par could use to compare the driving distances of the current and new golf balls. (include why you chose a 1-tailed or 2-tailed test)

      Analyze the data to provide the hypothesis testing conclusion. What is the test statistics and the p-value for your test. What is your recommendation for Par, Inc.?

      Provide descriptive statistical summaries of the data for each model as well as a histogram.

      What is the 95% confidence interval for the population mean of each model, and what is the 95% confidence interval for the difference between the means of the two populations?

      Do you see a need for a larger sample sizes and more testing with the golf balls? Discuss.

      Current

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    • profile image

      Whateve 8 years ago

      Who knows and who cares!

    • profile image

      Hewy 8 years ago

      Buddy get a life, were not here to do ur damn home work so don't put a full freakin page of numbers and questions up, sonia awnsered a simple question, take that and go with it b*tch.

    • profile image

      Hewy 8 years ago

      Martha iz a s1ut. hahahah

    • profile image

      Basheer 8 years ago

      Excellent

    • profile image

      Janice 8 years ago

      Wow! Thanks for clearing this up in english for us new calculators.

    • profile image

      Nadira 8 years ago

      thanx a lot for explaining the concept so well!!!!!!!!!!!

    • profile image

      Lindsey 8 years ago

      i have NO idea what u are talking about!!

    • profile image

      Camilla 8 years ago

      WHAT????? I'M GOOD AT MATHS AND THIS MAKES NO SENSE...I'M SO CONFUSED....:s

    • profile image

      pip 8 years ago

      just looking up to remember how to do this, this will make doing my boyfs homework a whole lot easier! i can prob even teach him this!

    • profile image

      Tommy 8 years ago

      You just saved me a hell of a lot of time on a project that is due tomorrow and possibly just saved my highschool GPA!

      THANKS A MILLION!

    • profile image

      mimi 8 years ago

      can anyone help me basically i have a report for uni to hand in that requires me to calculate standard deviation and as far as i remember when you take away the number from the mean the total should come to zero, like in the example, but mines is not working. My numbers are things like 6.3 x 10 to the power of 4. I really don't understand what i'm dong wrong. Help!

    • profile image

      george 8 years ago

      how do you calculate 2 and 3 sigma?

    • profile image

      Jade 8 years ago

      Thanks i'm currently revising for an exam and this was so straightforward and easy to grasp cheers!

    • profile image

      poop 8 years ago

      this is the worst advice ive ever seen

    • profile image

      softballgirl 8 years ago

      that was really helpful sonya thanks

    • profile image

      Dianne 8 years ago

      Thank you so much for this.

    • profile image

      Haterrr 8 years ago

      Poop, your name says it all. Your a moron. Sonya provides a good example that has helped many ppl. And thats all you can say is that its bad advice. Get a life...

    • profile image

      paval 8 years ago

      hey its so easy

    • profile image

      Lisa 8 years ago

      This was extremely helpful. Thank you so much for posting. This information made finding the SD easy!

    • profile image

      Cara 8 years ago

      Really helped, thanks!

    • profile image

      Elle 8 years ago

      Thank you so much! I hope you teach!!!! =))))

    • profile image

      Pravin 8 years ago

      Thank you hub page this is very easy method to find standard deviation

    • profile image

      Pravin 8 years ago

      Thank you, this methode is very easy to find out the S.D.

      I request you for find out the Standard deviation of the following numbers:

      -1.0628,-1.0857,-1.1169,-1.1443,-1.171,1.1981,-1.2254,-1.253,-1.2808,-1.309

      send the answer on my Email ID : pravin.hudge@yahoo.com

      Thank you

    • profile image

      Dom 8 years ago

      Hey, I am working on my masteres in engineering and was given the std deviation for a test score. I forgot how to calculate it thanks a lot. A few people asked what this means. +/-1 SD is another way of saying where "most" of the people fell in a given popluation if you can assume a standard "Bell" curve. For my example the avg was about an 81 with an SD of 12 this means that ~75% of the people had grades between 69 (81-12) and 93 (81+12). if you are within +/-1 SD deviation of MEAN (avg) you are considered normal or average (on a true bell curve these would be C students but few teachers use true bell curves). I am not as good at giving simple answers as sonia but I hope this helped. BTW Sonia I wish you had been my stats prof.

    • profile image

      Pariah 8 years ago

      Dom, are your from the UK? If so can you confirm if you ever lived in stockport?

    • profile image

      student 7 years ago

      well explained! now i know where i went wrong. i should be divided by (#item - 1)

    • profile image

      Maizita!! 7 years ago

      thanks u saved my math project!!

    • profile image

      Stats Exam In 3 days 7 years ago

      Great working... very beneficial.. thanks =-)

    • profile image

      math_teacher 7 years ago

      Quick comment- it doesn't matter if you substract each number from mean values or vice versa as you will square the number in next step so the value will be same.

    • profile image

      nima 7 years ago

      woww.so easy to understand.thank you to whomever thought of putting these examples.as iranians say DAMETGARM DADASH.

    • profile image

      another math teacher 7 years ago

      This has been pointed out, but I'd like to emphasize: if you're dealing with a population, then you divide by the number of values; if you're looking at a sample, you divide by n-1. So if the set you're looking at is actually all of the data, it's a population and you divide by the number of values. If you're just looking at a portion, you divide by the number of values minus 1.

      Also, there is an easy way to do it on a TI-83 if you have one:

      Go to Stat--> Edit

      If necessary, clear out L1 by pushing the up arrow until L1 is highlighted, then push Clear and Enter. Then, enter all of your data (push enter between each data value). To get out, type 2nd, Mode (Quit).

      Then go to Stat, arrow over to Calc, and choose 1-Var Stats; Enter, Enter.

      Sx gives sample standard deviation; the one that looks like ox (with a funny o, which math people call sigma) is the population standard deviation. You have to know which to use.

      Very nice explanation, Sonia; I hope this helps, too!

    • profile image

      Tamara 7 years ago

      Ok wondered if someone on here can help me! Everytime I try to work this out I get a different answer! I have a table of the average time a biological and non biological washing powder took to break down a stain in both soft and hard water. The bio took 15mins in hard water and 16mins in soft water. The non bio took 20mins in both cases. How do i work out the standard deviation from this?

    • profile image

      Tamara 7 years ago

      Its ok! I' ve just figured it out, i was using the numbers the wrong way round. Thank you for the workings out thought, explained it much better here than anywhere else!

    • profile image

      Alice 7 years ago

      Thank you sooo much I found this so helpful- Im doing my GCSE stats and this saved me from making a gihugic error with my mean. THANK YOU!!!!!!!!!!!

    • profile image

      Concerned Earth Inhabitant 7 years ago

      Hey guys, Please try to avoid going in public places like clubs, bars etc for next few weeks. Hopefully this way we can stop the swan flu virus from spreading. Thanks all.

    • profile image

      chris 7 years ago

      Anyone familiar with confidence intervals? Im studying for the CFA, and one of the learning sections says to calculate the confidence interval using a standard deviation, and the next says to calculate with the standard error.

      This must be an error, no?

    • profile image

      Brain at ease 7 years ago

      Brilliant explanation, Sonya.

      You probably just saved my college career.

    • profile image

      Brain at ease 7 years ago

      Brilliant explanation, Sonya.

      You probably just saved my college career.

    • profile image

      Sidason 7 years ago

      I love your tutorial on SD but there is a slight mistake... when dividing the sum of the square numbers which you would end up with 210 you should actually be dividing it by the number of deviations which is 6 not 5.

    • profile image

      MCC 7 years ago

      we still don't understand.

    • profile image

      we love maths 7 years ago

      do not understand

    • profile image

      7 years ago

      wow very nicely explained. saved me on my test.

    • profile image

      Psyturnine 7 years ago

      Nicely explained.

      BUt yet not helpful.

      :|

    • profile image

      siuva 7 years ago

      very easy,thank u

    • profile image

      Paiiige 7 years ago

      Thanks, i feel slightly more confident towards my statistics GCSE

    • profile image

      Hannah  7 years ago

      hey this website is great so glad i came across it just wondering if someone could please clear this up for me i cant remember how to do it..my caculator keeps coming up with numbers such 8.281E-03 when i take away the mean and square it, what does the E-03 stand for?????

      thanks!

    • profile image

      gorry 7 years ago

      MCC says:3 weeks ago

      we still don't understand.

      we love maths says:3 weeks ago

      do not understand

      why u guys so dumb

    • profile image

      tonghuyen 7 years ago

      HI martha. YOU CAN SEND FOR ME ASSIGMENT ABOUT STATISTIC, WHICH YOU QUESTION IN THÍ PAGE

    • profile image

      tonghuyen 7 years ago

      Par, Inc., is a major manufacturer of golf equipments. Management believes that Par’s market share could be increased with the introduction of a cut-resistant, longer-lasting golf ball. Therefore, the research group at Par has been investigating a new golf ball coating designed to resist cuts and provide a more durable golf. The tests with the coating have been promising.

      One of the researchers voiced concern about the effect of the new coating on driving distances. Par would like the new cut-resistant ball to offer driving distances comparable to those of the current-model golf ball. To compare the driving distances for the two balls, 40 balls of both the new and current models were subjected to distance tests. The testing was performed with a mechanical hitting machine so that any difference between the mean distanced for the two models could be attributed to a difference in the two models. The results of the tests, with distances measured to the nearest yard, follow.

      Formulate and present the rationale for the hypothesis test that par could use to compare the driving distances of the current and new golf balls.Analyze the data to provide the hypothesis testing conclusion. What is the p-value for the test? What is your recommendation for Par, Inc.?

      Current

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    • profile image

      tonghuyen 7 years ago

      send answer for me: my email " tong_huyen_89@yahoo.com"

    • profile image

      gory 7 years ago

      omg....thats rubbish....i was hopin for sumthin a lil more helpful

    • profile image

      thanks 7 years ago

      you helped me so much, I was so lost before I read this!

    • profile image

      mumbaikar 7 years ago

      nice simple and very well presented

    • profile image

      very well done 7 years ago

      this was very straight forward and easy to understand. Thank you very much!

    • profile image

      gigi 7 years ago

      Thanks for that brief but straight to the point explanation of getting the standard deviation. I need to know what does it mean by having a standard deviation of 6.4?

    • profile image

      Rita 7 years ago

      Thank you, Thank you, Thank you, you made it easy to understand!!!!

    • profile image

      Alexandra 7 years ago

      So much better than those CRAZY sigmas all over the place, and the n and the ridiculous amounts of variables.

      Everyone taking AP Stat truly thanks you.

    • profile image

      Okta 7 years ago

      ThnX!!!

    • profile image

      Sarah 7 years ago

      Thank you so much! You condensed an hour long lecture into a few simple steps! It is truly amazing how quickly...or slowly a professor can throw simplicity out the window!

    • profile image

      please clarify 7 years ago

      You really should clarify in the text that you are calculating a sample standard deviation, and not a population standard deviation. Because it is 5.92 for the population standard deviation. (210/6=35; sqrt(35)=5.92)

    • profile image

      jaised 7 years ago

      thnkz

    • profile image

      lisa 7 years ago

      wonderful thank you for helping me understand

    • profile image

      sage 7 years ago

      very helpful

    • profile image

      Elijah 7 years ago

      im taking math at syracuse university and we are learning standard deviation. my teacher explained this so horribly that i didn't understand it. this made it soooo easy for me to understand. looking at this, i litterally learned it in 1 minute

    • profile image

      Sabrina 7 years ago

      Fabulous article. I'm working on Data Management homework and this has really helped me understand it! Amazing job.

    • profile image

      Candace 7 years ago

      This helped A lot!!!!!!!!! :]

    • profile image

      Malori 7 years ago

      yea this reali helpd been stuggln with standard deviation for a while

    • profile image

      Viola 7 years ago

      Thanks a lot Sonia...!

    • profile image

      Asar 7 years ago

      Thanks a lot. This made things so must easier for me. Now why teachers do it this way.

    • profile image

      Jason 7 years ago

      I Agree with asar, if teachers showed us it this way i think no one would have a problem of understanding!! thanks.

    • profile image

      thank you sonia 7 years ago

      any one care to explain this step? "divided by one less than the number of items in the list: 210 / 5 = 42"

      is it because you're calculating the avrg standard deviation of all the nos. from the mean, that's why you do this ? or..?

    • profile image

      kirk 7 years ago

      first!

    • mayyam profile image

      mayyam 7 years ago

      thank you, this was very helpful.

      i've never had a teacher that explained it this way. they over complicate things and then wonder why the class average is a c.

    • profile image

      Kamal 7 years ago

      Great Job Sonia!!!

    • profile image

      Rob from Canada 7 years ago

      AWESOME!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

    • profile image

      Zeeshan  7 years ago

      i have a question please i wil appreciate if any1 help me in it

      Mean and the S.D. of a set values is 100 and 5. compute mean +-2 S.D. and Mean +-3 S.D.. alos we have to interpret the results in the light of empricial rule and chebychev's inequlity

    • profile image

      jl 7 years ago

      how do you know whether you are calculating a sample or a population deviation?

    • profile image

      jl 7 years ago

      how do you know whether you are calculating a sample or a population deviation?

    • profile image

      jl 7 years ago

      how do you know whether you are calculating a sample or a population deviation?

    • profile image

      pojong 7 years ago

      please help me to calculate below question

      x 0.06 , 0.01 , 0.01 , 0.00

      y 0.01 , 0.08 , -0.13 , 0.01

      z 0.01 , -0.13 , 1.16 , -0.08

      t 0.00 , 0.01 , -0.08 , 0.01

      What is the standard deviation in the determination of x,y,z

      and origin time

    • profile image

      pojong's mom 7 years ago

      hey you come on internet and try to get someone to do your homework. Pojong you are very very bad father is waiting for you!

    • profile image

      calvin 7 years ago

      THANKS! I needed this to calculate error for my calibration curve in my lab!

    • profile image

      Hamza 7 years ago

      thanks this helped a lot :)

    • profile image

      李村 7 years ago

    • profile image

      Kait 7 years ago

      THANK YOU.

      Much easier than the formula my stat teacher provided.

    • profile image

      StrifeHart 7 years ago

      Thanks SO much, you explained it such better than my math text did.

    • profile image

      hgfiY Jffdlax 7 years ago

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      EVADALI 7 years ago

      Sonia, all I can say is that I freaking love you!! Thanx for making it sooo easy!!

    • profile image

      sudeera 7 years ago

      really nice...thanks

    • profile image

      Bob 7 years ago

      Okay. I don't know if this was already answered in the comments as i don't want to read through all of them. There are two types of Standard Deviation. One is Population and the other is Sample. This article highlights the use of

      When you are calculating the population standard deviation (when all the numbers in the set are all of the values [30 people take a math test, and you have 30 values]):

      you divide by the total numbers in the data set (in my example, 30)

      _________________

      When you are calculating the sample standard deviation (300 people take the ACT test and here are 15 of the results):

      you divide by one less than the amount you have (in my case, 14)

    • profile image

      Bob 7 years ago

      oops. i didn't finish my sentence. this article uses sample standard deviation

    • profile image

      aline 7 years ago

      hello

      but why did you divided by one less than the number of items in the list?

      is it related to a sample or population?

      cause ive seen other examples and they just divided it by the numbe of items in the list

    • profile image

      A. Rajendra  7 years ago

      It is very easy to understand.Thank you f for giving simple example.

    • profile image

      Venosa 7 years ago

      It is very easy to understand.

    • profile image

      snickers 7 years ago

      I cant believe this actually helped me. Thanks...I hope I pass my test that I have tomorrow cause of this

    • profile image

      RANA 7 years ago

      THANK YOU SO MUCH,IT IS VERY EASY AFTER I READ THIS INFORMATIONS

    • profile image

      mz.hughez 7 years ago

      omg!!! Thanks sooo very much, this make so much sense and I got the right answer the first try. I'm taking stats after being out of highschool over 10 years ago. Thanks a bunch!!

    • profile image

      Supriya 7 years ago

      Nice example but why to substract 1 from the no of items in the list. Please tell me why variance is square & standard deviation is a square root of variance. I mean to say how to apply in a practical sense.

    • profile image

      Marvinmasterpiece 7 years ago

      Thats the law....it has been there before you were born.why ask why?

    • profile image

      King 7 years ago

      thank you whoever you are. Made my day a hell lot easier

    • profile image

      Sandip 7 years ago

      Its Very Very Simple Method To Understand For We INDIAN Students.. Thanks A Lot..

    • profile image

      lisa 7 years ago

      OMG been tryin 2 make sense of sd 4 wks u just helped me do it in 15 mins ne 1 tnx

    • profile image

      ash 7 years ago

      thankyou so much :D

    • profile image

      mason 7 years ago

      had enough of stats all together. thanks i guess my question wasn't aboust sd after all. still confused in the VA

    • profile image

      Wilson 7 years ago

      still the wilson from above. I was wrong in two aspects of my calculations. The geneRAL PRINCIPLE IS THAT I AM A DOUCHE REMEMBER THUS

    • profile image

      Vishal 7 years ago

      excellent

    • profile image

      thanksalotsonia 6 years ago

      thanks a lot sonia. very helpful

    • profile image

      Ruthie 6 years ago

      hey! thanks a lot your explanation was quite clear,thumbs up!!!

    • profile image

      Brandy 6 years ago

      Thank you so much, this is the only site of been to that actually makes sense. Very straightforward and informative.

    • profile image

      Ruthie 6 years ago

      This is awesome, love it! I'll just add a small correction, if you don't mind... Where you say "sum of deviations" you should say "sum of squared deviations." Thanks for this nice work!

    • profile image

      future pharmacist 6 years ago

      Perfect thank you so much

    • profile image

      Ira Sharma 6 years ago

      thank you..you saved me in my corporate finance class..:)

    • profile image

      Gabriel Ma 6 years ago

      THANKYOU!!!!!!!!!!!

      you saved me from my maths test =))

    • profile image

      Kevin 6 years ago

      Thanks for helping me finish my thesus.

    • profile image

      Ariel B. 6 years ago

      Like Kevin up there, I'm working on my thesis as well! This explanation was so simple and so easy. Thanks again for your help!

    • profile image

      felix 6 years ago

      you made it look very easy. I will need a stat book if you have made one.

    • Manna in the wild profile image

      Manna in the wild 6 years ago from Australia

      Good. Well done - that was short and simple.

    • profile image

      Sonny 6 years ago

      omg thank you i was trying to work this for hours.. but this was a great help.........THANK YOU

    • profile image

      hungarian girl 6 years ago

      Please help me: how can I calculate standard deviation from these datas?

      Number of TV sets owned:0,1,2,3,4,5

      Frequency: 1, 32, 32, 20, 7, 3

      Thanks a lot.

    • profile image

      tokcha 6 years ago

      Thanks for your help,simple is always the best!

    • profile image

      LOL 6 years ago

      LOL, this shit is shit..the worst inaccurate shit i have ever seen

    • profile image

      Ally 6 years ago

      What if ur given at grouped dat, does it apply the same formular, b'cos my lecturer told me that, when ur finding SD for un grouped ur using the same system as explained here bt for grouped u have to divide the X-square x the frequency, then u proceed,

    • profile image

      Craig 6 years ago

      Great example of Standard Deviation. Appreciate the help, thanks!

    • profile image

      TB 6 years ago

      Such a good example and explanation of standard deviation. thanks for this!

    • profile image

      DANIELLE! 6 years ago

      thanks this helped me make a brochure for my math final . you know how to explain it way better then my ignorant teacher!

    • profile image

      Janna 6 years ago

      Thank you sooooooooooooooooo much I have been trying to figure this out and it was driving me crazy this helped me so much

    • profile image

      Pete 6 years ago

      Very nice explanation and example. I'm going to learn statistics for the first time at age 72 and this is a great help. Thanks.

    • profile image

      Nayef  6 years ago

      hey Sonia... great job but this is only works for a little bit of numbers... use this it's better:

      for discrete [(b-a+1)^2 - 1]/12

      for continuous (b-a)^2/12

      *note: b= largest number , a= lowest

    • profile image

      weird 6 years ago

      horrible

    • profile image

      Taya 6 years ago

      Thank you soo much i had a big exam the next day and i couldn't understand Standard deviation. This helped a lot THANK YOU!

    • profile image

      ba 6 years ago

      great help better than the online instuctor

    • profile image

      Tassy 6 years ago

      OMG - I no wat im going

    • profile image

      wowwwww 6 years ago

      THIS IS COMPLETELY WRONG, A PERFECT EXAMPLE OF WHY THE SOURCE OF YOUR INFORMATION IS SO IMPORTANT!!!!

    • profile image

      Proof Reader 6 years ago

      Sonia, well done. i could easily follow your explanation. Thanks for posting the example.

    • profile image

      N.Ashok kumar 6 years ago

      Thanks a lot ... this is very helpful for me thanks a lot...

    • profile image

      N.Ashok kumar 6 years ago

      i hav one problem i need to calculate process capability for a mchine using these data plz anyone can help me... the data is lik this 5.24,5.22,5.22,5.22,5.22,5.22,5.23,5.22,5.22,5.22,5.20,5.21,5.23,5.20,5.22,5.22,5.22,5.22,5.20,5.22,5.22,5.22,5.22,5.22,5.22..... please help me

    • profile image

      Abbott 6 years ago

      Q.E.D. "Quite Easily Done."

    • profile image

      Provas Sarker 6 years ago

      impressive i got it worth learning.......thanks

    • profile image

      Dale Hafner 6 years ago

      OK, got it. The statistical calculator in the software program I am using offers 3 standard deviations to adjust some alarm limits. Is it just mulitplying the value by 3? Therefore 3 SDs in the example given above would be 6.48 X 3 =19.44. Correct or no?

    • profile image

      Miroslav 6 years ago

      I built a website uding this Method and its 100% correct

    • profile image

      Miroslav 6 years ago

      Hers the link to the website i built on this http://sapic.ath.cx/standard-deviation-calc

    • profile image

      Sarah 6 years ago

      Wow, thank you! This is my second Stat class and the only thing that has made sense.

    • profile image

      prashant 6 years ago

      thanks!! i have my GRE paper tomorrow!! and this helped me

    • profile image

      Steve 6 years ago

      Taking my GMAT in 2 hours. This probably saved a few points for me. Thanks!!!

    • profile image

      angie 6 years ago

      Thanks,You made my day

    • karimeldib profile image

      karimeldib 6 years ago from Dubai, UAE

      hi all,

      Why i am getting 6.34 instead of 6.48

    • profile image

      Femi 6 years ago

      This is quite straight forward

    • profile image

      sugar 6 years ago

      this is really perfect! thx sonia..i gt 6.48 too

    • profile image

      Smurf 6 years ago

      Thanks man!

      means a lot to know there are people like you out there that are willing to help others like me.

    • profile image

      Jason 6 years ago

      Much thanks !! very helpful.

    • profile image

      Nivedita 6 years ago

      hey thanks....it helped me a lot

    • profile image

      Abbas Muneer 6 years ago

      It's quite easy and straightforward. Thanks for refreshing my highschool Maths

    • profile image

      Msc.BioStatistics 611 (p.u) (Abbas Muneer) 6 years ago

      Good thank u

      It helped me a lot.

    • profile image

      sullivan anye ade 6 years ago

      Whoever did this...u a genius in explanation

    • profile image

      giirll89 6 years ago

      thanks u saved my life! stats exam in 12 hrs!

    • profile image

      Kdukpa 6 years ago

      Thanks for the posting and everybody's comments. I just had statistical class and this has helped me greatly.

      Thanks a lot again.

    • profile image

      PRABAGaRAN RENGANATHAN 6 years ago

      tankz bro.....

      itz very easy to catch up

    • profile image

      baylorbear 6 years ago

      THANK YOU. I HATE stats and this is the only thing so far that has made any sense. This one minute of reading has explained much more than my professor could ramble about for an hour.

    • profile image

      kevin 6 years ago

      There is an online tool to calculate std dev:

      http://www.miniwebtool.com/standard-deviation-calc...

    • profile image

      rach 6 years ago

      this really helped me with physics homework for my lab due tomorrow morning, thanks!!

    • profile image

      aayush  6 years ago

      thanks lifesaver :)

    • profile image

      watch harry potter the deathly hallows 6 years ago

      So happy I found this!

    • profile image

      Tony 6 years ago

      Very easy to follow. thanks.

    • profile image

      bang  6 years ago

      any body know the explanations for the equation. like why or how it was found. THE PROOF. 8th grader

    • profile image

      Armon 6 years ago

      Thanks this was very useful

    • profile image

      James 6 years ago

      I finally understand :D, I hope this works for that Russian theorem as well as empirical rule thing

    • profile image

      Steph 6 years ago

      Thank you, this post was so helpful, and I feel like I actually understand. I wish my stats professor could explain it this easy : )

    • profile image

      maegan 6 years ago

      what a great post!

      i can A's my test in stats cause that's the only lesson that i'm confuse of... if our prof. give us some quiz, i often cheat!!!hahaha...

    • profile image

      Renee' Roche' 6 years ago

      Wow I Actually Understand How To Do This Now! Thanks!

    • profile image

      noula 6 years ago

      very useful :) thanks

    • profile image

      Paul 6 years ago

      Isn't except spelled with a "C" in it OLE?

      Your first response to sonia says yes exept....or am I not reading it correctly?

    • profile image

      Midoryu 6 years ago

      So...what about significant figures?

    • profile image

      abbas muneer 6 years ago

      very informative and useful thanks

      Abbas Muneer Msc.Biostatistics 611-09 p.u

      abbasmuneer611@yahoo.com

    • profile image

      abbas munir 6 years ago

      its help me a lot thanks

      Abbas Muneer Msc.Biostatistics 611-09 P.U

      abbasmuneer611@yahoo.com

      abbasmuneer611@hotmail.com

    • profile image

      abbas muneer 6 years ago

      its makes me easy thanks

      Abbas Muneer Msc.Biostatistics 611-09 Punjab Univesity

      abbasmuneer611@yahoo.com

      abbasmuneer611@hotmail.com

    • profile image

      abbas munir 6 years ago

      thanks its so easy

      Abbas Muneer Msc.Biostatistics 611-09 Punjab Univesity

      abbasmuneer611@yahoo.com

      abbasmuneer611@hotmail.com

    • profile image

      camilla 6 years ago

      very helpfull =)

    • profile image

      Bob Segar 6 years ago

      Get a life losers!!!

    • profile image

      Lesley 6 years ago

      thanx for taking your time to help other in need.

    • profile image

      Meena 6 years ago

      thank you so much!!!

    • profile image

      Jack 6 years ago

      Well in, quite a good explanation!

    • profile image

      thinker 6 years ago

      u guys r so good

    • profile image

      Abbas Muneer ( Msc.Biostatistics 611-09 Punjab Univesity ) 6 years ago

      thank you

      abbasmuneer611@yahoo.com

      abbasmuneer611@hotmail.com

      Abbas Muneer Msc.Biostatistics 611-09 Punjab University.

    • profile image

      AbbasMuneer 6 years ago

      thank you

      abbasmuneer611@yahoo.com

      abbasmuneer611@hotmail.com

      Abbas Muneer Msc.Biostatistics 611-09 Punjab University.

    • profile image

      Tyler 6 years ago

      thanksssss! :)

    • profile image

      Maria Hernandez 6 years ago

      Thanks this really helped me with my math homework! i got a good grade on it! so thanks again! ;)

    • profile image

      Ruo 6 years ago

      The examle is straight forward and easy to understand. thx a lot. ^^

    • profile image

      john 6 years ago

      what if you are given a sample mean of 82, a variance of 112.5, and n=45

    • profile image

      Ansari 6 years ago

      It was really helpful, and pretty easy to understand, thanks :)

    • profile image

      Varun 6 years ago

      Thanks a lot! That was the simplest and easiest method of computing SD. Thumbs up!!

    • profile image

      tyrellb 6 years ago

      i am currently doing an independent research project, and my teacher failed to teach me how to do SD. this was very helpful for computing SD! thanks a bunch :)

    • profile image

      ZAM 6 years ago

      THIS HELP ME A LOT ON MY FINAL YEAR ESEARCH PROJECT.. THANKS..

    • profile image

      samad 6 years ago

      hello,thanks,this help me a lot on my exams,thanks.GOG may bless you

    • profile image

      Stephen 6 years ago

      This helped me so much. Having a teacher with a heavy spanish accent sucks. Im coming here for homework.

    • profile image

      JavaKid 6 years ago

      can anyone here help me how to estimate mean and standard deviation for group data using ogive?

    • profile image

      shazny 6 years ago

      tanx broder ....this was helpful

    • profile image

      syed 6 years ago

      Thank you very much.....this helped me a lot when i had no time and no one there to help me out

      Thanks

      Syed

      Iqra University- Karachi Pakistan

    • profile image

      Reddevil 6 years ago

      thaaaaanks

    • profile image

      Water 6 years ago

      Thanks a lot, helped in my biology practical after I forgot to bring my books! Good work. :)

    • profile image

      baris 6 years ago

      excellent tutorial, understood in 10 seconds... other links were crap when I googled it !

    • profile image

      beer 6 years ago

      Thanks a lot.

    • profile image

      face 6 years ago

      Thanks, helped a lot!

    • profile image

      dadah 6 years ago

      thanks sonia..:)it helped me to answer my big assignment.. kip it up

    • profile image

      TJ 6 years ago

      AWESOME!!!! Great POST! gonna pass my test now... lol

    • profile image

      thanksalot 6 years ago

      i could never understand this in class and this really made it so simple

    • profile image

      mad 6 years ago

      thanks so much! i hate when you can never understand math but this made it so simple.

    • profile image

      nathan 6 years ago

      what does sd mean to the data?

    • profile image

      santosh 6 years ago

      it's Nice

    • profile image

      Holger 6 years ago

      thanks you made it sooo much easier to understand,than these complicated stats books.!

    • profile image

      hno 6 years ago

      than you so much

      now i need ouation about t-test

    • profile image

      Gralenite 6 years ago

      kool example

    • profile image

      jayant 6 years ago

      very good and neat explination guys

    • profile image

      Jordie 6 years ago

      Thanks! :)

    • profile image

      jae 6 years ago

      huh i just started math and i cant understand

      plz explain further

    • profile image

      Lorrie 6 years ago

      Thanks for putting this out there to help others.

    • profile image

      Fendi  6 years ago

      Wow, very helpful. I was given a complicated formula to do this but this procedure made it so much easier! Thanks!

    • profile image

      karleena 6 years ago

      Thanks, any layman can easily understand how to calculate standard deviation!

    • profile image

      Dan 6 years ago

      Helped me a lot, thaaaaanks heaps!

    • profile image

      stevo 6 years ago

      Thank You sooo much, you def saved my college career!!!

    • profile image

      selena 6 years ago

      thanks for posting this whoever u are. twas helpful.

    • profile image

      reb 6 years ago

      Thanks so much for your help! :D

    • profile image

      brilliant 6 years ago

      u all are so pathetic ,u find this stuff tough ,shame on ur mathematical aptitude,learn sth from indians.

    • profile image

      Fembi 6 years ago

      This does what millions of stat teachers have been unable to do in decades!

    • profile image

      Vinayak 6 years ago

      Thank You, this was very helpful.

    • profile image

      5 years ago

      mnm,,mn,mm

    • profile image

      5 years ago

      nmn,,nm,nn

    • profile image

      Jonys 5 years ago

      I am doing a QM case and it has helped me

    • profile image

      |Trimbo 5 years ago

      yeah!

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      DGOZZLE 5 years ago

      what does the standard deviation actually find out

    • profile image

      kissmychicken 5 years ago

      yeah what does standard deviation come out with DGOZZLE

    • profile image

      kissmychicken 5 years ago

      yeah what does it actually find out. HELP!!!!!!!

    • profile image

      M Asif 5 years ago

      Interesting, Thanx

    • profile image

      kissmychicken 5 years ago

      YYYEEEAAAHHH!!!!!!!!!

    • profile image

      lorry 5 years ago

      HELP!

      I have read all f the above, but can't figure out what to do if I already know the standard deviation. Here is my problem:

      A supplier of lumber for home building sells construction-grade 2-by-4 lumber in 8-foot lengths. Because of irregularities in the wood and shrinkage caused by drying, there is some variation in actual length. Lumber is acceptable if it is between 95.5 and 96.5 inches. The current process produces lengths that are normally distributed with a mean of 96.04 inches and a standard deviation of .52 inch. Is this process capable of meeting standards of acceptability?

      How do I figure this out?

    • profile image

      sarah 5 years ago

      I LOVE YOU THANKS

    • profile image

      siobhan 5 years ago

      erm... negative six squared would equal negative 36? not 36?

    • profile image

      siobhansaretard 5 years ago

      lawwwwl @ above comment. think realllllllly hard about what happens when you multiply 2 negatives together genius....sooo.....ermmmm....urafuckingidiot.

    • profile image

      poopster 5 years ago

      the comments on here are hillarious...

    • profile image

      Benster 5 years ago

      Ahhhhh this helped me!

    • profile image

      mattias 5 years ago

      so freaking confusing. sorry my math teacher can teach better than this and she sucks crap. sorry, but you need to be able to write this better so kids can actually understand

    • profile image

      matias 5 years ago

      not really its easy to understand

    • profile image

      dick penisten IV 5 years ago

      mattias ur fcking stupid. u in special program or something? this sht is easy like ur mom. god ur retarted

    • profile image

      kira 5 years ago

      what the hell that wasn't my damn question

    • profile image

      br3t 5 years ago

      Just got some more points on my exam! thanks

    • profile image

      Oluwalana Mike 5 years ago

      Its a gra8 help to me. TXS

    • profile image

      Avneel 5 years ago

      Very nice example, thanks

    • profile image

      hey 5 years ago

      but the answer is wrong. should be 5.91 sth... cos it's over 6, not (6-1) i.e. 5 for step 6.

    • profile image

      C2W 5 years ago

      For me,it is the easiest and the best tanx...Good work

    • profile image

      Qasim 5 years ago

      Sonia! Thank you...

    • profile image

      lenieke 5 years ago

      Hey great, many difficult explanation on the web, but this example makes sense :)

    • profile image

      jesereth 5 years ago

      It was simple yet helpful information. Thanks!

    • profile image

      Adham 5 years ago

      Thanks for the easy to understand example; I just have one wonder which I am clear about:

      Why we need to divided by one less than the number of items in the list: 210 / 5 = 42??? Is it just the role; to always divide the total of all deviations by one less than the total/sum of all items in the list? Please clarify.

      Thanks a lot,

      Adham

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      ELVIS SHIVHALO 5 years ago

      JA WELL,THAX 4 HELPIN ME,BUT HEY THERE IS STILL SOME CONFUSION IN THIS,MAYBE SOMEBODY CAN TRY ANOTHER METHOD

    • profile image

      Dennis 5 years ago

      Hey thnx I was very impress with d way u explained SD

    • profile image

      :) 5 years ago

      Thanks. Helped out tons

    • profile image

      madds 5 years ago

      omg thank you so much!! this is great!

    • profile image

      Sunday John Bosco 5 years ago

      I have got the point but why do you "divided by one less than the number of items in the list" I am confused there.

    • profile image

      Magarac 5 years ago

      Wow Sonja, you rock. YOU should be teaching my Statistics course, not the doofus who's getting paid by my university to do it! :-)

      Thank you!

    • profile image

      Statlover 5 years ago

      that method is epic so cool

      it is sorta different in school. This is nice and easy.

    • profile image

      mars 5 years ago

      wow, lot of comments on here.

    • profile image

      Andrea Noisternig 5 years ago

      Oh my god, soo good explained! If only all math teachers could be that detailed.

      THANKS

    • profile image

      cin 5 years ago

      it's very clear thank you sooo much!

    • profile image

      Melissa 5 years ago

      Just wanted to add to the long list of THANK YOUS! Doing a bloody stats unit :)

    • profile image

      Deedee 5 years ago

      That formula had me soooo confused but you made it so simple! Thanks so much!

    • profile image

      Samuel 5 years ago

      Thanks a lot. i passed my test thanks to you.

    • profile image

      irene 5 years ago

      I can my exam comfortably thank you Sonia

    • profile image

      Amanda 5 years ago

      I totally prayed to understand how to calculate standard deviations and found this site! AMAZING example!!! I could not understand how to calculate standard deviations until reading this right now! Love it, thanks a bunch! Jesus is AWESOME!

    • profile image

      zainab 5 years ago

      That is exactly what I was looking for!!

      Thanks a lot :)

    • profile image

      Esther Ripplinger 5 years ago

      I agree with the other one who said,"This is exactly what I needed!" I misinterpreted the formula. It left me wondering, but walking me through it is exactly what I needed. Thank you!

    • profile image

      Jeff 5 years ago

      The description was simple and the example you provided helped tie it all together. Great job.

    • profile image

      emma 5 years ago

      wow! awesome! you're AMAZING

    • profile image

      kaye 5 years ago

      Thanks for that explanation, you make it sound so easy, i am currently doing an Ass. Deg. and this statistics is killing me, but u certainly cleared that up for me, by the way after doing all of that what is the next step.

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      AngaNaa 5 years ago

      OMG!!!! Thank you SO much. This was very helpful and now I can work on mastering this technique for my Operations Management Test that is coming up. I had forgotten how to do standard deviations and lost my notes from my statistics class to refer back to it! What a life saver!!

    • profile image

      Lee 5 years ago

      Good Job, Thumbs up from me, needed clarification i was doing this right, and you did a great job of it

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      Anon 5 years ago

      well there is a catch. we only divide by one less than the numbers in the list only if our list is a sample. we divide by the exact number of items in our list if our list is the population, not a sample

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      Prasad Ajinkya 5 years ago

      We have written a post on how Standard Deviation is applicable in Finance, especially when doing an analysis in Excel. Do check it out - http://www.edupristine.com/blog/what-is-standard-d...

      Comments and feedback invited!

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      Musa simon 5 years ago

      Interesting!!!

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      Dabee 5 years ago

      I need some one to help me how to caculate SD when i have 2 value in a sample

      For exemple:

      A=3.3 and 3.5

      B=3.2 and 3.4

      C=3.4 and 3.4

      D=3.3 and 3.1

      If some one know please help me and send me the formula on my e-mail address as dabee_chiakua@hotmail.com

      Thank you very much

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      gangsta 5 years ago

      omg its thugtastic yo

    • profile image

      Maria 5 years ago

      THANK YOU SO much! I have an exam tomorrow and ALL semester I NEVER got it until now :)

    • profile image

      Max 5 years ago

      Thank you very much.

    • profile image

      Ikram Ahmad 5 years ago

      Thanks

    • profile image

      easin 5 years ago

      thank u so so so so so so much

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      5 years ago

      can the standard deviation and the range of a set of data ever equal??

    • profile image

      hehehehe 5 years ago

      THANK YOU SO MUCH!!!!!!!!

      The example school gave was kind of confusing, and when I was reviewing I couldn't understand.

    • profile image

      SATHISH 5 years ago

      SIMPLY EXCELLENT

    • profile image

      Buddy 5 years ago

      I'm sure it's been mentioned but I didn't read every post. This is the method for finding a sample standard deviation. If you're finding a population standard deviation you divide by the number of observations, not n-1.

    • profile image

      Hetty 5 years ago

      Thank you for this!

      Helped me with applied science coursework!

    • profile image

      SUCK MY EAR 5 years ago

      THIS IE A PIE AND IT IS LIKE A LLAMA WHO EATS YOUR UNDERWEAR WHEN YOU ARE NOT LOOKING

      In otherwords, this is EPIC POTATO :)

    • profile image

      Devon 5 years ago

      Stupid

    • profile image

      I do your mum 5 years ago

      No one will me read my comment;)

    • profile image

      Jye 5 years ago

      Thanks so much. Helping out my year 12 math.

    • profile image

      Sarah N 5 years ago

      The only reason I will be passing my stats test tonight is because of you! Thank you so much. I wish my teacher could break it down like this :/

    • profile image

      Lene 5 years ago

      that was awesome.

      short,sweet,to the point. AND easy to understand.

    • profile image

      EE 5 years ago

      Thanks

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      ganesh 5 years ago

      X f dx dx2 fdx fdx2

      40 12 10 100 120 1200

      Here every thing i understand 3rd raw dx i don't understand any body help for this...

    • profile image

      Garry 5 years ago

      Superb. Nice and easy to follow, thank you

    • profile image

      yuva 5 years ago

      very interesting and nice example thank u

    • profile image

      ellie 5 years ago

      Thanks!!It was easy to understand because you broke it down step by step THANKS for the help!!

    • profile image

      geezel 5 years ago

      thank you so much.it really helps me.

    • profile image

      Anil Singh 5 years ago

      Thanks Sonia. Now i can say its simple to calculate SDEV.

    • profile image

      Math is terrible 4 years ago

      Thank's Sonia! God bless you! It helped a lot when i did my math homework!

    • profile image

      thanks this kinda helped 4 years ago

      this was pretty good

    • Drax profile image

      des donnelly 4 years ago from NYC....

    • profile image

      Olivia 4 years ago

      Pls i have this assignment help me. 55+53+80+53+56+90+70+78+80+85 in a standard deviation

    • profile image

      Apples 4 years ago

      55 53 80 53 56 90 70 78 80 85

      Mean = 700/10=70

      difs = 15 17 10 17 14 20 0 8 10 15

      squares of difs = 225 289 100 289 198 400 0 64 100 225

      sum of squares of difs = 1890

      sum of squares of difs/(number of things-1) = 1890/9 = 210

      standard deviation = root(210) = slightly less than 14.5

      Do not hold me to mathematical accuracy, I am not currently with a calculator (hence the approximation of the final answer)

    • profile image

      Apples 4 years ago

      You should verify that this is the formula that your class is using though, another common version divides the second part by just the "number of things" instead of "number of things - 1".

      This gives us 1890/10=189

      root(189) = 13.something, probably around 13.7.

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      Jonathan 4 years ago

      Is 42 the variance in this case?

    • profile image

      Daina 4 years ago

      thanks 4 such a great effort itx really help 4 d readerx

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      Math Gal 4 years ago

      this is incorrect!

      you do not divide by one number less than the number of items in the list, you divide by the number of items in the list.

      the correct standard deviation for this problem is approximately 5.916.

    • profile image

      Afshan 4 years ago

      awesome!!! you're the man!

    • profile image

      Nunu Norbert 4 years ago

      u just saved me from failing my stats examx thanx a lot

    • profile image

      Tommy 4 years ago

      Thank you, OMG

    • profile image

      Dawnysha 4 years ago

      Why do you divide by 5 and not 6? (at the end)

    • profile image

      RESPECT BOY 4 years ago

      PLS CAN YOU ARRANGE EVERYTHING IN ROLLS AND COLUME,AND SHOW THE FORMULAR DETAIL?

    • profile image

      michaelheemson 4 years ago

      hi there tommy if your still knoking around i think this is the contact

      and some info , they have a deal on at the mo , mention michael hiltams put you on

    • profile image

      sean 4 years ago

      cheers, very easy to understand

    • profile image

      FOSTOM 4 years ago

      MIND WIDE OPEN!

      GREAT JOB......

    • profile image

      Lee 4 years ago

      I would like you help me about my final report free test. I don't know how can I do students deviation or standard deviation below:

      360 all of students for free test in final report

      108 group of sample in final report

      score of group sample for free test there are 15 questions.

      list of students score:

      22 students got 1 score

      23 students got 2 score

      30 students got 5 score

      10 students got 7 score

      10 students got 9 score

      10 students got 13 score

      3 students got 15 score

      Please use determine the standard deviation by using the function bellow:

      SD= ?(( N?fx^2 - (?f?x)?^2) )/?( 2@N))

    • profile image

      MiddleSchooler 4 years ago

      I find it interesting everyone seems to be in high school or going into college. I'm in 6th grade and learning this. Lol, too many big words from other websites. I CAN FINALLY GET MY HOMEWORK DONE! Thank you.

    • profile image

      lauren 4 years ago

      Thanks so much! that was easy to understand

    • profile image

      ben 4 years ago

      no thats wrong you don't divided by one less than the number of items in the list you just divide by the same number of numbers in the list

      that the right way.

    • profile image

      Lucy 4 years ago

      Thank you! I completely understand now. Based on the comments, it seems like lots of people are doing this in High School maths. I wonder why we need it in 6th grade maths? Also, is there a real-world use for standard deviation?

    • profile image

      kabirdes 4 years ago

      The explanation was Awsm sonia :)

      Can u plz explain where do we use it..?

    • profile image

      Sal Stephens 4 years ago

      You rock Sonia! Great explanation!!!!!

    • profile image

      agabrans 4 years ago

      I'm trying to figure out this problem from school. Your explanation of Standard Deviation was awesome. I seriously understand it now! Is it possible to figure out this problem? I don't see the mean or list of numbers that I THINK I need. Thanks!

      You have collected 11 water samples. The variance of the sample is 47.3084. What is the standard deviation of the sample (4 decimal places)?

    • Andrew Laughton profile image

      Andrew Laughton 4 years ago

      Thanks so much for the explanation!

    • profile image

      Vincent 4 years ago

      YEs i finally knows now

    • profile image

      thegoofyblue 4 years ago

      omg this is the best thing ever! THANK YOUUUUUU

    • profile image

      roboporno 4 years ago

      every calculator i go on says when i square a negative it comes with a bigger negative, help?

    • InterestCaptured profile image

      InterestCaptured 4 years ago

      This is perfectly explained, thanks a lot

    • profile image

      hanaa ibrahim 4 years ago

      i have a question says : if the standard deviation of the numbers X1, X2, .....,Xn is 4 , find the standard deviation of the numbers : X1 -2, X2-2,.....,Xn-2

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      Trevor 4 years ago

      agabrans, it is 14.2640

    • profile image

      Ramin 4 years ago

      Thanks a lot saved me the test :D

    • profile image

      nkiran 4 years ago

      I don't understand why to divide the sum of squares by "by one less than the number of items in the list" and not by "number of items in the list". I find the latter logical.

    • Goldenserenity profile image

      Goldenserenity 4 years ago

      Thank you! I read the chapter on this in my math book and I didn't have a clue. I went through your post once and I understand it. You are awesome!!

    • profile image

      Jack Knowell 4 years ago

      Its interesting wish it was explained with some graphics and more examples as it was explained on http://www.jpfis.com

    • profile image

      bastillandude 4 years ago

      how could i compute the standard deviation of this data

      no. of respondents

      survey 3 - Very 2 - Satis 1 - Poor

      question good factory

      1 40 2 0

      2 38 2 2

      3 37 5 0

      .

      .

      .

      .

      i need asap

      thanks

      1.

    • calculus-geometry profile image

      TR Smith 4 years ago from Eastern Europe

      Just noticed my statistics tutorials are getting a lot of incoming visits from this article. The comment thread here is 100 times longer than the actual hub, lol.

    • profile image

      sigmund 4 years ago

      very helpful. thanks.

    • profile image

      Shannon 4 years ago

      THANK YOU! This has been the first time in over a year I have been able to understand this!!

    • profile image

      sarDeemsgen 4 years ago

      We helpful to obtain at the top of living however as of late We have developed a new opposition.

    • profile image

      Quintana 4 years ago

      If you calculate the standard deviation by hand, you will likely end up having to use a calculator anyway for the last step in computing the square root. So why not just use a calculator for the whole thing?

      http://www.wolframalpha.com/input/?i=population+st...

      http://www.had2know.com/academics/variance-standar...

      or

      http://www.calculatewhat.com/math/statistics/varia...

      At least you can avoid computational errors. The only errors you might make are in entering the data. While it's good to know the general method and formula for standard deviation, I don't think calculating it by hand is practical or wise for a set with more than 10 numbers. You can also use something like Excel or Calc (open source spreadsheet program that comes with Open Office.)

    • paxwill profile image

      paxwill 4 years ago from France

      It just goes to show you how much emphasis search engines place on old content. This hub shows up higher in searches for standard deviation because it's over 6 years old, but there are much better s.d. tutorials on HubPages, even if they happen to be younger.

      For instance, this hub doesn't explain the difference between population and sample s.d., that is, when you divide by n and when you divide by n-1 before taking the square root. Here are hubs that offer better explanations:

      https://hubpages.com/education/Statistics-Made-Eas...

      https://hubpages.com/education/Statistics-Formulas...

    • profile image

      Krishley 3 years ago

      Calculating standard deviation is not really difficult but can get quite complex when you have lots of numbers. I'm currently preparing for my A-Level statistics paper and i use this calculator to check my answers : http://standard-deviation-calculator.en.softonic.c...

    • profile image

      rj 3 years ago

      thanks fr the help

    • profile image

      hmm, 3 years ago

      divide by n or n-1?

    • profile image

      rebecca 3 years ago

      perfect explanation. thanks

    • profile image

      PRINCE 3 years ago

      Thanks to my virtual tutor, simplicity is the ultimate sophistication

    • profile image

      rebecca 6 months ago

      ¯\_(ツ)_/¯

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