[R] MA / RMA / Type II regression?

[Peter Dalgaard BSA]

"Pete St. Onge" <pete at seul.org> writes:

> Are there functions in R for Major Axis and Reduced Major Axis regression? I
> have OBS-RESID graphs of two of my regressions showing a linear increasing
> trend, indicating the inappropriate use of Type I regression; I upgraded to
> R 0.90.1 and after looking through the help pages, didn't see anything that
> seemed what I needed. LQS didn't quite seem what I was looking for.

(What is MA/RMA regression? I don't know them, not by that name
anyway.) I hope you plotted FIT vs. residuals there and not really OBS
vs. resid. The latter are well-known to generate apparent linear
relations when none is in fact present, especially when the original
relation is weak, as in.

x<-rnorm(20)
y<-0.01*x + rnorm(20)
plot(y ,residuals(lm(y~x)))

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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