Gustaf,
I would be advisable to first check that such z scores are valid
statistically (I have my doubts). They make a number of assumptions,
chief among them being that un-normalized weight is not a proper
physiologic summary. It is almost always the case that joint modeling
of age and weight (e.g., ANCOVA) works better.
Frank
Gustaf Rydevik wrote:
Hi all,
I've got a project where I have to calculate weight-for-age Z-scores,
preferably using the WHO standards.
WHO have been very nice to publish macros for doing this in both
STATA,SPSS, SAS and Splus formats
(see http://www.who.int/childgrowth/software/en/), but for some reason
have chosen not to use the free R alternative to Splus.
In the Splus zipfile there are nine datafiles with a "sdd" file
ending, presumably data dumps from Splus 7.x. I've tried using
restore.data from the foreign package, but that does not work
(probably because the data is saved in the newer format).
I'm considering trying to read in spss files and massaging them to fit
to the format that the splus macro is expecting, but I'd prefer to be
able to use the Splus files directly.
Has anyone on the list tried using the WHO anthro macros with R, and
can tell me how they did it?
Alternatively, could some, very kind, person try and open the Splus
files, and save them in a R-readable format?
I would be extremely grateful for any help on this.
Best regards,
Gustaf Rydevik
--
Frank E Harrell Jr Professor and Chairman School of Medicine
Department of Biostatistics Vanderbilt University
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