Conditional calculation of the standard deviation.

[TPFKAS]

Hi there,

I have a table with two columns (a1:b200).
I need to calculate the standard deviation of the values in column B, but only for those values where a condition in column A is being met.
For example: column A contains only the numbers 0 and 1 and I want only to include all numbers in column B in the calculation of the standard deviation where the value in column A is 1.

Can this easily be done with a single formula?

Thanks in Advance!

 

[Eric W]

Sure, for example:

	A	B	C	D	E
Col A	Col B

<colgroup><col style="width: 25pxpx"><col><col><col><col><col></colgroup><thead>
</thead><tbody>
[TD="align: center"]1[/TD]

[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]2[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]748[/TD]
[TD="align: right"][/TD]
[TD="align: right"]307.8[/TD]
[TD="align: right"]342.1146[/TD]

[TD="align: center"]3[/TD]
[TD="align: right"]1[/TD]
[TD="align: right"]328[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]4[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]833[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]5[/TD]
[TD="align: right"]1[/TD]
[TD="align: right"]876[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]6[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]820[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]7[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]511[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]8[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]441[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]9[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]943[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]10[/TD]
[TD="align: right"]1[/TD]
[TD="align: right"]824[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]11[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]575[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]12[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]974[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]13[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]811[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]14[/TD]
[TD="align: right"]1[/TD]
[TD="align: right"]99[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]15[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]494[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]16[/TD]
[TD="align: right"]1[/TD]
[TD="align: right"]174[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]17[/TD]
[TD="align: right"]1[/TD]
[TD="align: right"]870[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]18[/TD]
[TD="align: right"]1[/TD]
[TD="align: right"]890[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]19[/TD]
[TD="align: right"]1[/TD]
[TD="align: right"]182[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]20[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]97[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]21[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]493[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]22[/TD]
[TD="align: right"]1[/TD]
[TD="align: right"]390[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]23[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]44[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]24[/TD]
[TD="align: right"]0[/TD]
[TD="align: right"]567[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

[TD="align: center"]25[/TD]
[TD="align: right"]1[/TD]
[TD="align: right"]165[/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]
[TD="align: right"][/TD]

</tbody>

Sheet4​

[TABLE="width: 85%"]
<tbody>[TR]
[TD]Worksheet Formulas[TABLE="width: 100%"]
<thead>[TR="bgcolor: [URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=DAE7F5]#DAE7F5[/URL] "]
[TH="width: 10px"]Cell[/TH]
[TH="align: left"]Formula[/TH]
[/TR]
</thead><tbody>[TR]
[TH="width: 10px, bgcolor: [URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=DAE7F5]#DAE7F5[/URL] "]D2[/TH]
[TD="align: left"]=STDEV.S(B2:B25)[/TD]
[/TR]
</tbody>[/TABLE]
[/TD]
[/TR]
</tbody>[/TABLE]

[TABLE="width: 85%"]
<tbody>[TR]
[TD]Array Formulas[TABLE="width: 100%"]
<thead>[TR="bgcolor: [URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=DAE7F5]#DAE7F5[/URL] "]
[TH="width: 10px"]Cell[/TH]
[TH="align: left"]Formula[/TH]
[/TR]
</thead><tbody>[TR]
[TH="width: 10px, bgcolor: [URL=https://www.mrexcel.com/forum/usertag.php?do=list&action=hash&hash=DAE7F5]#DAE7F5[/URL] "]E2[/TH]
[TD="align: left"]{=STDEV.S(IF($A$2:$A$25=1,$B$2:$B$25))}[/TD]
[/TR]
</tbody>[/TABLE]
Entered with Ctrl+Shift+Enter. If entered correctly, Excel will surround with curly braces {}.
Note: Do not try and enter the {} manually yourself[/TD]
[/TR]
</tbody>[/TABLE]



If your standard deviation formula is D2, then the E2 array formula only includes the values where column A = 1. Make sure to enter it with Control+Shift+Enter.

 

[TPFKAS]

Thanks for your prompt reply.
Works like a charm. I was just reading some stuff about array operations. Never knew about it before. Another extra piece of wisdom. ?

 

[Eric W]

I don't think anyone knows all the tricks of Excel! Arrays are particularly obscure, and particularly useful! Glad this one works for you.