Dear Abdalla,

SPSS does this by the usual way - group (sample) sizes are included into the formulas which calculate t statistics and its degrees of freedom. You can see these formulas in SPSS algorithms, statistics textbooks, wikipedia, etc.

Raimundas Vaitkevičius

Vytautas Magnus University, statistician and lecturer

=====================
To manage your subscription to SPSSX-L, send a message to

[hidden email] (not to SPSSX-L), with no body text except the
command. To leave the list, send the command
SIGNOFF SPSSX-L
For a list of commands to manage subscriptions, send the command
INFO REFCARD