Hi everyone,
Today I have an issue that I do not find a solution.
I have the following summary list:

CompID N. Staff
1001 5
1002 3
1003 2
1004 1

The first column is company ID and the second the number of staff working on
that company, if appplying STDEV(N. Staff) I obtain 1.707825.
So far so good.

I have the extended list from above:

CompID StaffID
1001 67
1001 2
1001 89
1001 22
1001 98
1002 70
1002 65
1002 9
1003 29
1003 97
1004 63

So, for the company 1001 there are 5 individuals, etc.

Based on the second list (this is key) I need to calculate the STDEV that
give me the result, i.e. 1.707825

I have try different things with array formulas but it does not work for me.
Please could anyway suggest me the sytax of such formula (if possible).

Many thanks in advance.
F