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loess smoothing question

2 messages · Thomas L Jones, Bert Gunter

Thomas L Jones
# 
I am trying to smooth a dataset with evenly spaced values of x, 
perhaps using loess smoothing or something similar. However, the y 
values are hypergeometrically distributed; I think I want to use a 
logarithmic link function. It falls under the general heading of 
non-parametric regression. The problem is of interest in predicting 
the demand at a voting place, in order to avoid long lines.

Questions: Should I use loess smoothing?
           Do I want a logarithmic link function? If so,
           How do I tell loess to use a logarithmic link function?

Tom, a newbie to the R project, and not really a statistician
Bert Gunter
# 
If the y values are "hypergeometrically" distributed then they are counts,
right? Loess is designed for continuous, reasonably symmetric data, and so
is inappropriate. You should probably consider GLM for a parametric fit; or
perhaps GAM for a nonparametric fit. As the data appear to have the
structure of a time series, you may wish to search CRAN for a non-Gaussian
time series package. I am unfamiliar with such methodology, so I have no
idea what, if anything, is available for this.

Better suggestion. Get help from a local statistician, at least to get you
started.

-- Bert Gunter
Genentech Non-Clinical Statistics
South San Francisco, CA
 
"The business of the statistician is to catalyze the scientific learning
process."  - George E. P. Box