It is not entirely clear what you are using for y values in smooth.spline, but it would appear that it is just the point estimates. I would suggest using instead -- at each x value -- a few equally spaced quantiles of the estimated proportions. Implicitly, smooth.spline expects to be fitting a mean curve to data that has constant variance, so you might also consider reweighting to approximate this, as well.
url: www.econ.uiuc.edu/~roger Roger Koenker email [EMAIL PROTECTED] Department of Economics vox: 217-333-4558 University of Illinois fax: 217-244-6678 Champaign, IL 61820 On Aug 10, 2007, at 10:23 AM, Rose Hoberman wrote: > Sorry, forgot to attach the graph. > > On 8/10/07, Rose Hoberman <[EMAIL PROTECTED]> wrote: >> I am looking for a function that can fit a smooth function to a >> vector >> of estimated proportions, such that the smoothed value is within >> specified confidence bounds of each proportion. In other words, >> given >> a small number of trials and large confidence intervals, I would >> prefer the function to vary smoothly, but given a large number of >> trials and small confidence intervals, I would prefer the function to >> lie within the confidence intervals, even if it is not smooth. >> >> I have attached a postscript file illustrating a data set I would >> like >> to smooth. As the figure shows, for large values of x, I have few >> data points, and so the ML estimate of the proportion varies widely, >> and the confidence intervals are very large. When I use the >> smooth.spline function with a large value of spar (the red line), the >> function is not as smooth as desired for large values of x. When I >> use a smaller value of spar (the green line), the function fails to >> stay within the confidence bounds of the proportions. Is there a >> smoothing function for which I can specify upper and lower limits for >> the y value for specific values of x? >> >> Thanks for any suggestions, >> >> Rose >> >> <smoothProportions.ps> > ______________________________________________ > R-help@stat.math.ethz.ch 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. ______________________________________________ R-help@stat.math.ethz.ch 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.