Andy and John,
I looked at typical when xlevels did not work but when I saw that it was a function I went no further. Setting the function to a constant was a good idea.
John's method seems to require that I change the model:
> eff <-effect("sex*age",mod,xlevel=(Age=c(120,120)))
Error in all(!(factors[, term1] & (!factors[, term2]))) : subscript out of bounds
In addition: Warning message: sex:age does not appear in the model in: effect("sex*age", mod, xlevel = (age = c(120, 120)))
Andy's method works as suggested for this simple case.
Thanks for your time.
Cheers, David
______________________________________________ [EMAIL PROTECTED] mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html
