Dear Sarah, [snip...] "I know that samples within each facility cannot be treated as independent, so I need an approach that accounts for (1) clustering within facilities and"
You could just use lm() & some planning. The data from within a specific facility can be fit with a model to generate parameters that are compared between facilities. Not to practical though - assuming the 57 production facilities each have their own analytical lab, you'll have 57 different fits to get your parameters from to use in your between test. Questions about dependent data are fairly common, so it should be relatively straight forward to get a solution and/or idea for a suitable package from the archives. "(2) the different number of samples taken at each facility." It's a waste of time to worry about that. You'll be comparing aggregate values between groups, and you'll have too few data-points within a group to detect within effects... [snip...] Sincerely, KeithC. ______________________________________________ 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.
