I am doing a sequential multiple regression where I start with the base
model: y = a + b1x1 + b2x2
followed by the full model: y = a = b1x1 + b2x2 + b3x3 + b4x4
==================================================
Try findit hireg and install this program. It does what you want if I
understand you correctly.
Alan Acock
I just looked at -hireg-.  Something to be careful of: It does not do a 
listwise deletion of missing data for all variables in the final model, 
e.g. I just did a test where the first regression had 500 cases and the 
addition of more variables shrunk the N to 405 cases.  I believe you should 
be analyzing the same cases throughout it you are going to do incremental F 
tests like this.