[R] best way to calculate per-parameter differences in across-subject means
René J.V. Bertin
rjvbertin at gmail.com
Wed Aug 2 16:41:27 CEST 2006
I have some data in a data.frame where for each of a number of
subjects, I have scores for all of a number of symptoms.
Subjects are subdivided in a number of groups, which have unequal sizes.
I'd like to plot between-group differences in the scores on the
various symptoms. Ideally, that would be in a form as would be
> bwplot( Score~Symptom )
but I'm not sure one can say anything about the distribution of
differences when the sample sizes differ as much as they do.
So I will start plotting the per-group differences in the per-symptom
Is there a better way (rather than using loops) to get a table of
those per-symptom means, something like
> with( subset(dat, group==1, drop=FALSE), Score~Symptom )
Thanks in advance,
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