Standard Deviation and weighted average of a subset with duplicate values

[vjayf1]

Hi, I have a data set which has subsets having duplicate values like this:

Customer	Score
1	0.253
1	0.253
1	0.253
1	0.356
1	0.356
2	0.245
2	0.245
2	0.378
3	0.425
3	0.425
3	0.235
3	0.235
3	0.39
3	0.38
3	0.39
4	0.45
4	0.45
4	0.51
4	0.52

<colgroup><col width="64" span="2" style="width:48pt"> </colgroup><tbody>
</tbody>

I used the formula =STDEV(IF($A$2:$A$34894=A2,$B$2:$B$34894)). But it gives me the same standard deviation value for the entire set.

Can someone please help me with an appropriate formula?
Also, if i have weights for each individual row, is there a formula that can give me a weighted average for each subset?

Thanks in advance!

 

[AhoyNC]

Your formula is an array formula and must be entered with CTRL-SHIFT-ENTER.

Put the cursor in the cell with the formula.
-press F2 to edit
-then CTRL-SHIFT-ENTER.

Excel Workbook
	A	B	C	D
1	Customer	Score
2	1	0.253		0.093729
3	1	0.253		0.056415
4	1	0.253
5	1	0.356
6	1	0.356
7	2	0.245
8	2	0.245
9	2	0.378
10	3	0.425
11	3	0.425
12	3	0.235
13	3	0.235
14	3	0.39
15	3	0.38
16	3	0.39
17	4	0.45
18	4	0.45
19	4	0.51
20	4	0.52
Sheet