Question: how to calculate pooled standard error in excel?
Answer: Open a new Microsoft Excel spreadsheet.
Enter your first set of data into column A of the Excel spreadsheet. ... 
Enter your second set of data into column B. ... 
Type "=(N-1)*(STDEV(A1:Bxx)^2)" in cell C1. ... 
Type "=(N-1)*(STDEV(B1:Bxx)^2)" in cell C2. ... 
Type "=c1+c2" in cell C3.
Type "=sqrt(C3/(Na+Nb-2)) in cell C4.