On Sat, 16 Jan 2010, Vera wrote:
Thanks for your help so far, everyone.
Thomas: I haven't looked very deep into the survey package yet, so I
don't know if what I'm looking for is actually missing or if I just
haven't found it yet.
What is "missing", from my point of view at the moment, is some kind
of global weighting function that allows me to set a weight and then
just perform different kinds of analyses without thinking about it any
more.
There isn't anything like this, because it isn't possible. Some analyses can't
sensibly be done with sampling weights; for others you can get point estimates
but it is hard to get standard errors.
I'll try to describe what I want to do:
I'll be working with the European Social Survey datasets (for my MA
thesis). The data have to be weighted before doing any kind of
analyses because the sample sizes in the different countries aren't
proportional to total population sizes.
Analyses I probably will do include: contingency tables, measures of
association (Cramer's V), factor analysis, linear regression.
I've used SPSS so far and thus haven't ever had to look very deep into
what 'weighting' means, exactly.
The survey package has weighted contingency tables (with tests) and linear
regression. If you don't need tests, xtabs() in base R will also do weighted
contingency tables.
The factanal() and princomp() functions can take as input a weighted version of
the covariance matrix, and this can be produced by cov.wt() or by svyvar() in
the survey package.
-thomas
Thomas Lumley Assoc. Professor, Biostatistics
tlum...@u.washington.edu University of Washington, Seattle
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