With the help of J. Baron's search engine, I found an old thread on reduced major axis regression (see below). Prior to my creating a really awkward function to accomplish RMA regression, I was wondering if anyone might clarify Dr. Ripley's casual comments below. On Fri, 4 Feb 2000, Pete St. Onge wrote: >.......My > understanding in the latter is that it minimizes the squares of both the > horizontal and vertical distances from the regression line, and thus do not > impart any particular 'accuracy' to the predictor variable. .... Ripley wrote: ...The sum of squares of horizontal and vertical distances i just Euclidean distance^2 to the projection on to the line, so this is just PCA. Use princomp and take the first principal component. ****My question...take and do what with it? thanks very much, Henry Martin Henry H. Stevens, Assistant Professor 338 Pearson Hall Botany Department Miami University Oxford, OH 45056 Tel: (513) 529-4206 FAX: (513) 529-4243 http://www.muohio.edu/~botcwis/bot/henry.html -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._