[R] Are you experienced in SAS ...

Prof Brian Ripley ripley at stats.ox.ac.uk
Mon Nov 26 19:47:41 CET 2001


On Mon, 26 Nov 2001, kjetil halvorsen wrote:

>
>
> Peter Dalgaard BSA wrote:
> >
> > Rolf Turner <rolf at maths.uwa.edu.au> writes:
>
> >
> > Not the sort of thing to make Doug and Jose happy. They've probably
> > heard these sentiments before, though.
> >
> > But... There's an important difference between the two
> > implementations, exactly in the area of strata. These are BTW really
> > just "levels" in the sense of multilevel models (pupils within classes
> > within schools within municipalities within countries, etc.) and their
> > explicit specification makes some block-diagonal matrix optimizations
> > possible. For largish data sets, you will find that SAS loses out
>                                     --------------------------------
> > efficiency-wise, because it doesn't do these optimizations.
>      --------------
>
> Only a related question. Anybody have experience with lme with large
> data sets? Specifically, I have a data set with almost 60000
> observations.
> Anybody used lme with something like this? And, what kind of computer
> would be necessary? Thats relevant for me, for I amabout to buying a
> neqw box.

Yes, I have but only with simple models in a machine with 1Gb RAM.
On the other hand, I would tend to analyse such large datasets in pieces:
they are not usually homogeneous.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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