Hi again! I have a data.frame with the columns y, x1, x2, x3. I would like to fit linear models with one variable at a time, then 2 variables at a time, and then 3. Makes me think of a power set. Anyhow, is there a function to produce the right hand side of the formulas, please? thanks, Laura Holt mailto: lauraholt_983 at hotmail.com R Version 2.1.0 Windows