How to Calculate Pooled Standard Deviations in Excel

By Carter McBride

Microsoft Office allows you to perform complex functions in Microsoft Excel. For most calculations, Excel has a set function you can use. Excel does have a standard deviation function, which you need to calculate pooled standard deviation. However, there is not have a pooled standard deviation function you can use. Since there is no pooled standard deviation function, you need to recreate the formula in steps across several different cells. This will save you the time of calculating pooled standard deviation by hand.

Step 1

Open a new Microsoft Excel spreadsheet.

Step 2

Enter your first set of data into column A of the Excel spreadsheet. Use one cell for each data entry.

Step 3

Enter your second set of data into column B. Use one cell for each data entry.

Step 4

Type "=(N-1)*(STDEV(A1:Bxx)^2)" in cell C1. Replace N with the number of data entries you have in column A. Replace xx with the cell location of the last data entry in column A. For example, if you had 25 cells taken up in column A, you would replace N and xx with 25.

Step 5

Type "=(N-1)*(STDEV(B1:Bxx)^2)" in cell C2. Replace N with the number of data entries you have in column B. Replace xx with the cell location of the last data entry in column B.

Step 6

Type "=c1+c2" in cell C3.

Step 7

Type "=sqrt(C3/(Na+Nb-2)) in cell C4. Replace Na with the number of data entries you have in column A. Replace Nb with the number of data entries you have in column B. The result in C4 is the pooled standard deviation.