How does Stdev works in qlik view?

[#1]

Hi

I tried drilling down on the function stdev and I found out that it is equal to stdev.s of excel.
Excel has 2 ways of calculating standard deviation 1)Stdev.P  2)Stdev.S.

I would like to show how these works. Let us suppose we have 2 nos. 85 and 90.

so if i use Stdev.P ans is 2.5 and that has to be the ans

if i use Stdev.S ans is 3.34.

and the same ans 3.34 is given by qlik view Stdev formula. Isnt it wrong? please guide me

[swuehl · Accepted solution]

For large sample sizes, both Excel functions converge. Neither is wrong, it depends on how you derive the mean value (estimate or not). For more details, you should talk to a statistician of your choice.

You can transform Stdev.S into Stdev.P by calculating something like

Stdev.S * sqrt(N-1) / sqrt(N)  = Stdev.P

N being your sample size (count of values).

[#3]

Thanks for enlightening me with the conversion forumla..so simple yet requires common sense which i lack a bit...

I was trying from the whole day to write the big whole formula of Stdev.P(taking avg then summing it up then sqrt and all) in qlik view.