Hi Ivo,

You might check out biglm.  It is not clear to me how to parallelize a single 
model, but if you are running several, of course you can (but you already know 
that).  The one thing that may help is to link R against an optimized, 
multithreaded BLAS such as Atlas (I think you have to do this at compile time, 
but I could be gravely mistaken).

Another possibly very silly idea is that if you are running many models with 
different combinations of your variables (sort of a model selection type 
thing), rather than fitting the model every time, what about creating a dataset 
with all variables (including interactions) of interest, and calculation one 
huge covariances matrix and the means.  Then you just fit all your models based 
off the covariances matrix.  That could still be huge and maybe not anymore 
computationally efficient, but it would effectively reduce your working data 
from n x k to k x k (+ 1 x k for the vector of means if you care about those).

Josh

On May 8, 2012, at 20:30, ivo welch <ivo...@gmail.com> wrote:

> dear R experts---now I have a case where I want to estimate very large
> regression models with many fixed effects---not just the mean type, but
> cross-fixed effects---years, months, locations, firms.  Many millions of
> observations, a few thousand variables (most of these variables are
> interaction fixed effects).  could someone please point me to packages, if
> any, that would help me estimate such models?  (can these problems be split
> over many different cores?)
> 
> advice appreciated.
> 
> /iaw
> 
> ----
> Ivo Welch (ivo.we...@brown.edu, ivo.we...@gmail.com)
> CV Starr Professor of Economics (Finance), Brown University
> http://welch.econ.brown.edu/
> 
>    [[alternative HTML version deleted]]
> 
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