On Fri, 6 Jul 2012, MacQueen, Don wrote:
So what you're faced with is that the cenros() function has no built-in methods for grouping or subsetting -- unlike some other R methods, especially those that work with the lattice package, or the many modeling functions like lm() that have a subset argument or employ a conditioning syntax for models [like y ~ x | g ]. In effect, this means you have to roll your own.
...
This is obviously just an outline.
Don, Yes, I do need to work out how best to address the needs of two current projects. This will take some time as I've not before needed to work with censored data (regulators tend to focus on only threshold exceedences). As a result, I'll be re-reading Dennis's book (the second edition) and the NADA.pdf, defining exactly what I need, trying various approaches, and certainly coming back here for advice and suggestions. One thing I noticed a couple of days ago is that I could use cenboxplot() for chemical concentrations by period, but could not figure out how to change the x axis lables from Pre and Post (or Before and After, I forget the exact terms) to more meaningful terms. This will be an interesting journey and a great education for me. Thanks, Rich -- Richard B. Shepard, Ph.D. | Integrity - Credibility - Innovation Applied Ecosystem Services, Inc. | Helping Ensure Our Clients' Futures <http://www.appl-ecosys.com> Voice: 503-667-4517 Fax: 503-667-8863 ______________________________________________ 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.
