In Excel 200, I have 2 columns of numbers.
I want to calculate the mean and standard deviation of all of those
numbers in column 2 for which the corresponding numbers in column 1
match a certain criterion, e.g.
Mean and SD of all in column L where where Fn=10
For the mean, I can do it thus
[here my criterion is in cell P6 rather than being specified as a
here an array formula is being used to calculate the numerator.
But if I try to calculate the standard deviation with an equivalent
I get an answer 10 times too small.
What syntax should I be using, or do I have to do it an entirely
different way (e.g. with sums of sqares and squares of sums, as per
the base formula for SD?