How to Calculate Standard Deviation
94To 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
Step 2a
Just hit enter
The Mean or Average will now appear in Cell 11
Step 2a - Photo 2a
Step 3
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
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..
Amazon - Excel
|
New Perspectives on Microsoft Office Excel 2007, Comprehensive
Price: $76.19
List Price: $105.95 |
|
Microsoft® Office Excel® 2007 Step by Step (Step By Step (Microsoft))
Price: $13.98
List Price: $24.99 |
|
Microsoft Office Excel 2007: Comprehensive Concepts and Techniques (Shelly Cashman Series)
Price: $69.92
List Price: $101.95 |
|
Special Edition Using Microsoft(R) Office Excel 2007
Price: $22.35
List Price: $39.99 |
PrintShare it! — Rate it: up down [flag this hub]
thanks Iðunn
After i read your the page, i'm able to finish my statistic project..thankx dude
hey chopiex_bilaz', no problem.. the power of the Net, isn't it great... cut copy and paste that homework...
th creepy man is realy CREEPY. you should take him off the page.
thanks Chad, yes I must go in for a new identity some of these days
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*
Love it, Drax.....the SD calculations, the Excel and the especially the poetry!! ;-)
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..
awesome man!
thanks KK, I really really must do more of these....
Hey Mndheather - thanks for the comment, Drax...
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....
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...
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... :)
CD and today (Mon May 19th) it is 93.. maybe some of these days I'll sit down and plot this...
thanks Drax..
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.
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....
thnx a lot for such a small and easy way of understanding the standard deviation.
Abhinav I'm glad it was useful to you.... tell others... thnaks Drax
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!
Hey Tori, nice of you to say so, thanks very much... Ciao Drax
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.
all right Cem, good that this continues to be useful... thanks for the comment..
Thank you so much...
how to calculate the IRR?
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.
Hey Rowan, thanks, glad it was of use to you, I hate that when teachers cannot get the knowledge across...
Can you tell me why it's( Deviation) devided by n-1 but not by just n. What does it really mean?
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
Thank you for sharing the steps to calculate the standard deviation. You rock!
hey great user name, thanks for the thanks regards drax
Thanks heaps for this example! It's by far the easiest to understand. I now understand Standard Deviations! lol.
Hi Matt,
thank you very much for the comment, it is always nice to get encouragement.
Regards
Drax
Iðunn says:
3 years ago
nicely done~