> From what you have written, I am not exactly sure what your > seat-of-the-pant sense is coming from. My pantseat typically does not > tell me much; however, quartic trends tend to less stable than linear, > so I am not terribly surprised.
My pantseat is not normally very informative either, but if you saw the width of the confidence limits I'm getting for the quartic coefficient, I think your pantseat would agree with mine. :-> The confidence band is staggeringly wide, many times the variation in the data itself; and with 300,000 data points to fit to, that just should not be the case. With that many data points, it seems quite obvious that one can be "95% confident" that the true data lies within a band somewhere reasonably close to the band that the sample data actually fall into, not a band many times wider. > As two side notes: > > x_qt <- x^4 # shorter code-wise > and you can certain just enter a quartic term if the data is just > quartic and you are not really itnerested in the lower trends. Yep, for sure. Thanks! Ben Haller McGill University http://biology.mcgill.ca/grad/ben/ ______________________________________________ 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.
