Conditional Standard Deviation

[yongshun]

I wish to calculate the standard deviation of Brand A Product 1-5 and Brand B Product 1-5.
Is there any shortcut for this?
I call this a brand pairing and I have 300 brand pairing to be done. Help is needed!

Brand	Product	Demand
A	1	3
A	2	4
A	3	12
A	4	35
A	5	6
A	6	8
A	7	9
A	8	5
A	9	6
A	10	7
B	1	10
B	2	12
B	3	3
B	4	4
B	5	6
B	6	3
B	7	67
B	8	9
B	9	5

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[joeu2004]

Since everything is ordered, the simplest formulas are:

Brand A: =STDEVP(C2:C6)
Brank B: =STDEVP(C12:C16)

But I presume you are looking for something more general.

Array-enter (press ctrl+shift+Enter instead of just Enter) the following formulas:

Brand A: =STDEVP(IF($A$2:$A$20="A",IF($B$2:$B$20={1,2,3,4,5},$C$2:$C$20)))
Brand B: =STDEVP(IF($A$2:$A$20="B",IF($B$2:$B$20={1,2,3,4,5},$C$2:$C$20)))