I did the following in Excel. Row 3 contained results for the treatment group. Row 4 had results for the comparison group. F columns had group averages. J columns had standard errors.
Average score difference
Pooled standard error
|T-value (absolute value)||If t-value greater than 1.96 (alpha=5%)|
|=F4-F3||=SQRT( ( (J3*J3) / G3 ) + ( (J4*J4 ) / G4 ) )||=ABS(N3/O3)||*|