[R] analysing data with case weights: rejoinder
tlumley at u.washington.edu
Fri Nov 15 20:02:50 CET 2002
On 15 Nov 2002, Peter Dalgaard BSA wrote:
> Thomas Lumley <tlumley at u.washington.edu> writes:
> > On Fri, 15 Nov 2002, bojaniss wrote:
> > > Hello,
> > >
> > > Based on replies (which I'm gratefull for) I guess the only solution
> > > is to create a package, that will contain function to build
> > > lm()-like linear models, and allow weighting cases (as I described
> > > two days ago).
> > >
> > > This would also alow buliding those models for data in aggregated
> > > form without a need for using e.g. expand$grid().
> > >
> > There's no problem with data in aggregated form, only with probability
> > weighting.
> Depends on what you mean with "aggregation" doesn't it? If you have
> "replication weights" (counts of data with given value), I think you
> still have problems.
There's no problem for categorical data, which is the case where you
most likely to have counts of data with given value.
With a linear model you can aggregate further to get an average value over
each covariate pattern and then have variance weights
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