Formula to calculate Std Dev based on column value

[OmniBlue]

Please see the attached file, which is an excerpt of my data. I would like to calculate the standard deviation for each Item number (each item has 10 scores). However, because my data set contains MANY rows, I do not wish to enter the STDEV formula manually for each Item, as is done in the attached file. Is there a simple formula you could suggest which would automatically fill in STDEV for each Item?

Thank you!

[JohnTopley]

Try ..

=STDEV(IF($A$3:$A$47=D3,$B$3:$B$47)) where D3 contains Item number: D3=1, D4=2, D5=3 so put in E3 and copy down

Enter with Ctrl+Shift+Enter

[OmniBlue]

Thank you, John. However, the formula results in a divide-by-zero error, which doesn't make sense to me since it doesn't involve division.

[JohnTopley]

See attached. Problem is your item numbers which appear to be text. Change to numbers. I forgot to mention this in my earlier post.

[JohnTopley]

Just to be clear on the last point: I put numbers 1 to 3 in D3 to D5 and they did not match with your item numbers which were text. So I changed the item data to number format. If the item data is numeric just ensure that the format is the same as that in "D" cells if you use the same approach.

[OmniBlue]

Thank you so much!