Ok thanks Jim - I'll give it a go! I'm new to R, so I'm not sure how I'd go about performing averages in subsets... I'll have a look into it, but any subsequent pointers would be gratefully received as ever!
I'll also try playing with it in Access, and maybe even Excel 2007 might be able to do the trick too? Thanks again...! Steve ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
