How to Calculate Standard Deviation

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By Drax

To Calculate Standard Deviation ;-

1. Get the Mean

2. Get the deviations

3. Square these

4. Add the squares

5. Divide by total numbers less one

6. Square root of result is Standard Deviation

1. get the Mean

to begin you need the mean or the average, for example add 23, 92, 46, 55, 63, 94, 77, 38, 84, 26 ... = 598 divide by 10 (the actual number of numbers) 598 divided by 10 = 59.8

so the mean or average of 23, 92, 46, 55, 63, 94, 77, 38, 84, 26 is

59.8

____________________________________________________

2. get the deviations

subtract the mean from each of the numbers, the answers are;-

-36.8, 32.2, -13.8, -4.8, 3.2, 34.2, 17.2, -21.8, 24.2, -33.8

____________________________________________________

3. square these

to square means multiply them by themselves, the answers are;-

1354.24, 1036.84, 190.44, 23.04, 10.24, 1169.64, 295.84, 475.24, 585.64, 1142.44

____________________________________________________

4. add the squares

total of these numbers is 6,283.60

____________________________________________________

5. divide by total number of numbers less one;-

you had 10 numbers less 1 is 9 numbers

so 6283.60 divided by 9 = 698.18

_____________________________________________________

6. square root of result is Standard Deviation

square root is the number multiplied by itself to get 698.18 which is:-

26.4 so 26.4 is the Standard Deviation...

_____________________________________________________

Ok so above is the manual method of doing this

_________________________________________________

...below is the step by step example using Excel...

Step 1

Enter your range of numbers as shown in cells 1 to 10..

Step 1 - Photo 1

Step 2

place the cursor in Cell 11

go to the menu bar, select insert, select function - the insert function dialog box opens.

Click on the category and select Statistical

In the window below select Average

hit enter

Step 2 - Photo 2

Select the Insert Function

Step 2a

When you hit enter another dialog box will appear asking you to confirm the range, i.e. the numbers in cells 1 to 10 that you wish to perform the calculation on.

Just hit enter

The Mean or Average will now appear in Cell 11

Step 2a - Photo 2a

Step 3

Place the cursor in Cell 12

same as before Go to the menu bar, select insert, select function

The function dialog box will open, select statistical, in the window below scroll down and select STDEV

Step 3 - Photo 3

Step 4

When you hit enter another dialog box will appear asking you to confirm the range, i.e. the numbers in cells 1 to 10 that you wish to perform the calculation on. Since it automatically seeks to perfrom the calc on all the cells above you will have to change the range from D4:D14 to D4:D13

The Standard Deviation will now appear in Cell 12

Step 4 - Photo 4

Pat yourself on the back if...

your final calc matches this...

and the Final Score is...26.4

Ok So What Good is it?

Wiki say;-

Standard deviation may serve as a measure of uncertainty. etc etc and I went WTF does that mean (and I am a statistical / Excel head) http://en.wikipedia.org/wiki/Standard_deviation

The Last Word

Just say we were using Deviation to analyse hub scores, in the example below all the hub scores are above 90, when the SD is calculated for this range the SD is 2.92. this is low, as a contrast the original calc has hub scores from 23 to 94 in other words there is a lot of volatility...

So if one wished to rank hubpages it may be that those with a lower Standard Deviation i.e. less volatility are more consistent... and so enter the esoteric world of statistics... imagine this was horses....

An Example of Using SD

after all that ..some poetry from Drax..

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Iðunn says:
3 years ago

nicely done~

Drax says:
3 years ago

thanks Iðunn

chopiex_bilaz' says:
2 years ago

After i read your the page, i'm able to finish my statistic project..thankx dude

Drax says:
2 years ago

hey chopiex_bilaz', no problem.. the power of the Net, isn't it great... cut copy and paste that homework...

chad says:
2 years ago

th creepy man is realy CREEPY. you should take him off the page.

Drax says:
2 years ago

thanks Chad, yes I must go in for a new identity some of these days

Drax says:
2 years ago

yo folks, I have edited this to show the procedure manually and then using Excel, plus you can go and get the actual spreadsheet if you want and by the way Drax is a poet.... who somewhat ironically likes Excel... *laughs*

Mystic Biscuit says:
2 years ago

Love it, Drax.....the SD calculations, the Excel and the especially the poetry!! ;-)

Drax says:
2 years ago

Hey Mystic Biscuit, great name... thanks very much, I should do more of this Excel stuff some of these days since it is almost a form of relaxation...

..Drax..

kk says:
2 years ago

awesome man!

Drax says:
2 years ago

thanks KK, I really really must do more of these....

mndheather says:
2 years ago

very very informative, illustrated in a very simple way.

http://www.jasfy.com

Drax says:
2 years ago

Hey Mndheather - thanks for the comment, Drax...

CarpetDiem says:
2 years ago

hi Drax, you should write a hub on how to get a hub score of 100. Wow!

I cheat and use my calculator to get a standard deviation. One thing I think that you could add to this hub (if you wanted to, but it is already a 100) is a bell curve graph to show the significance of standard deviation. If I remember correctly from school (a long time ago), x% of the data will fall within plus or minus 1 std dev, y% plus or minus 2 std dev, and I think its 99.7% will be within plus or minus three std dev. If you have enough data to calculate an accurate std dev, you can then determine the likely values of any new incoming data - would be good for a hub on how to make a living in Las Vegas...

Now about how you get that score of 100....

Drax says:
2 years ago

CD thank you for the great suggestion, I must revise this again... with regard to the 100 I think it relates mostly to incoming hits from google searches, when they are high the score is high so there is a correlation of sorts there....

Thanks Drax...

CarpetDiem says:
2 years ago

Drax, I see that this hub is now a 91. Interesting that the hub score fluxuates based on the number of incoming hits. I wonder what the standard deviation of the fluxuation on this hub is... :)

Drax says:
2 years ago

CD and today (Mon May 19th) it is 93.. maybe some of these days I'll sit down and plot this...

thanks Drax..

Sarah says:
2 years ago

A word of advise, as a University academic, do not use wikipedia to get your answers as most of the time the information is just presented from people, and not from trustworthy sources.

Drax says:
2 years ago

thanks Sarah... hmmm... as a university academic it might be good to know the distinction between advise and advice.. I like wikipedia, especially because it is not perfect or does not pretend to be. This is much better than say Govt pretending that everything they say is truth....

abhinav says:
2 years ago

thnx a lot for such a small and easy way of understanding the standard deviation.

Drax says:
2 years ago

Abhinav I'm glad it was useful to you.... tell others... thnaks Drax

Tori says:
17 months ago

Wow, exactlly what i needed help in THANK YOU i just got an A+ on my HW =D... your example is the simpliest out there on the web, and easyest 2 understand, thanks again!

Drax says:
16 months ago

Hey Tori, nice of you to say so, thanks very much... Ciao Drax

CEM says:
16 months ago

Hey there,

THANKS for this!!! Loved the pic editorial, it was very helpful and easy to understand. I finally got it (at least I hope so) after many frustrating tries.

Drax says:
16 months ago

all right Cem, good that this continues to be useful... thanks for the comment..

Polong says:
15 months ago

Thank you so much...

Polong says:
15 months ago

how to calculate the IRR?

Rowan says:
14 months ago

cudn't ask for a better explanation. Thanks a million. Got an awful teacher who confused the entire topic (like everything else he teaches.) Got an exam tomorrow and jst conceptualised it. You may have just saved me from failing the exam. Thank you sincerely. Loved the poems as well.

Drax says:
14 months ago

Hey Rowan, thanks, glad it was of use to you, I hate that when teachers cannot get the knowledge across...

Es says:
14 months ago

Can you tell me why it's( Deviation) devided by n-1 but not by just n. What does it really mean?

Drax says:
13 months ago

Hey ES to be perfectly honest I have no idea but I will go and look it up just as soon as I have time and I'll post the answers here within a few weeks..

Thanks Drax

Grateful Alive says:
12 months ago

Thank you for sharing the steps to calculate the standard deviation. You rock!

Drax says:
12 months ago

hey great user name, thanks for the thanks regards drax

Matt says:
10 months ago

Thanks heaps for this example! It's by far the easiest to understand. I now understand Standard Deviations! lol.

Drax says:
10 months ago

Hi Matt,

thank you very much for the comment, it is always nice to get encouragement.

Regards

Drax

Noor says:
6 months ago

Chrisssssssssssssss U'r Owsaaaam, U really help me xxxxxx

Dots... says:
5 months ago

Thanks. Really helps in schoolwork.

Drax says:
5 months ago

Hey Dots... use the technology... cut that homework time in half... :-)

seb says:
5 months ago

cheers drax you're my hero.

Sexy jonty says:
5 months ago

Very well written hub .....

very much informative ......

Thank you very much for your great hub, for good advice, good wishes and support. Thanks for sharing your experience with all of us.

Drax says:
5 months ago

Hey thanks very much Seb

Regards Drax..

Drax says:
5 months ago

Hey thanks Sexy... ;-) Regards Drax..

clever man says:
4 months ago

hi Drax..... i read alot of sites about(Calculate Standard Deviation) but i cuod not understand...

now after i read your page understand 100%

great explanation

Excel explanation very great

its all Really helps

thanks a lot

( pls forgave me for my bad inglish)

Drax says:
4 months ago

thanks man, nice to get a compliment from a Clever Man :-)

great name..

Cheers

Drax

clever man says:
4 months ago

hi Drax..... thanks for your reply

i wonder if you can help me in the following :

Linear Regression Indicator ...

calculation....

how To do linear regression indicator with excel

again and again thanks a lot

Ahmer says:
3 months ago

DUDE THE SQUARE ROOT IS NOT THE NUMBER MULTIPLIED BY ITS SELF

eric says:
2 months ago

this is great, thanx for making it easy

Drax says:
2 months ago

no problem Eric, it's great that this hub has proved to be helpful to everybody...

Areif says:
2 months ago

Its really cool way of explaining! This is simple this is useful, you made complex definition to simple and understandable. Good Job.

Drax says:
2 months ago

Hey Areif... thanks for the comment and delighted it was of some use to you...

no point says:
4 weeks ago

It doesn't answer the question how to _calculate_. It just tels what the deviation is.

Drax says:
4 weeks ago

Well No Point... if you read it and follow the 6 steps telling you how to calculate it then you can apply the same rules to any set of numbers... ? so it tells you how to do it step by step...

1. Get the Mean

2. Get the deviations

3. Square these

4. Add the squares

5. Divide by total numbers less one

6. Square root of result is Standard Deviation

Topic	Replies
how is pi an irrational number when it can be expressed as 22/7.....posted by sunnyraghvendra	2
probabilityposted by seanorjohn	8
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How to Calculate Standard Deviation

1. Get the Mean

2. Get the deviations

3. Square these

4. Add the squares

5. Divide by total numbers less one

6. Square root of result is Standard Deviation

to begin you need the mean or the average, for example add 23, 92, 46, 55, 63, 94, 77, 38, 84, 26 ... = 598 divide by 10 (the actual number of numbers) 598 divided by 10 = 59.8

2. get the deviations

square root is the number multiplied by itself to get 698.18 which is:-

Links

Step 1

Step 1 - Photo 1

Step 2

Step 2 - Photo 2

Step 2a

Step 2a - Photo 2a

Step 3

Step 3 - Photo 3

Step 4

Step 4 - Photo 4

Pat yourself on the back if...

and the Final Score is...26.4

Ok So What Good is it?

The Last Word

An Example of Using SD

after all that ..some poetry from Drax..

Amazon - Excel

How to calculate standard deviation

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