Standard Deviation Math Problem 1324

[Br3tt96]

So I obviously know how to get the mean, but I'm not sure how to get the Standard Deviation. 

 

[Dash Lambda]

The standard deviation is the root of the variance, which is the average of the squared deviations.

 

So, basically, you average the values you get from squaring the difference between each entry and the mean, and take the root of that.

[CBojorges]

You can do the sum of the squares minus the squared mean instead of doing the subtraction and then squaring them. 

[D-Dos Dan]

If you don't have to show working then open up a spreadsheet (Excel, google sheets, etc) for the sake of the argument I use Google so I will use those commands not sure if it is different in excel. Put your data in 2 columns then in a random box type "=stdevp(" then highlight the y series of plots so the independent variable then press comma "," and highlight the other series of plots and close bracket and you're done.

 

There are several other methods for standard deviation which give a different result so I am assuming you're using the common one which is stdevp.

[Dash Lambda]

21 hours ago, CBojorges said:

You can do the sum of the squares minus the squared mean instead of doing the subtraction and then squaring them. 

How exactly is that different?