Conditional standard deviation in excel - please help!
 

Hi

I have my excel dataset arranged as follows :

K T
APPLE .....
ORANGE .....
APPLE .....
ORANGE .....


In Column K, I have fruit data which is either APPLE or ORANGE.

In Column T, I have corresponding numerical values.

Each row has apple followed by orange data successively.

Rows of data are added each day.

In column W, I'm trying to compute the standard deviation of the last 7 days worth of numerical values but for specific fruit in the samw row of column K.

So if the fruit in K20 is Apple, W20 must calculate standard deviation of the past 7 numerical values of just apples. In K21, the same computation is done for Orange.

How do I solve this with a simple line of code?

I have tried the following :

The code I have in row W557 is :

{=IF($K543:$K556=K543,STDEV.S($T543:$T556))}

This is not giving me correct values of standard deviation.

What am I missing?

Thanks a lot for your help.