repeated measures: levels of grouping factor must be less than number of obs

Just to clarify, when you say repeated measures do you mean that you have
data from multiple individuals from the same family? ?Or do you mean that
you have data on the same individuals across multiple time points (ex. data
from person one on Monday, and Tuesday, and Wednesday, etc.)? ?The latter is
what is more traditionally referred to as a repeated measures study; the
first is simply clustering in the data.

If the first (i.e. the clustered data), the model you have specified is
sufficient. ?Specifically, it will estimate a variance component that will
tell you how much variation there is in y between family groups.

Hope that helps.

Andrew Miles


On Apr 18, 2011, at 11:33 AM, Brent Pedersen wrote:

hi, I posted this to the main R mailing list a while back and people
directed me to
the lme4 package and this mailing list so I thought I might get more
help here...

We have some data, a subset of which is pasted at the end of this message.
I am trying to understand how to do repeated measures as our study
design consists of a subject (proband) and 1 or 2 siblings.

Thus far, our model looks like this--with family_id indicating a
sibling relationship:

model = lmer(y ~ concordant + age.proband + age.other + sex.proband +
sex.proband + sex.other + (1| family_id), data=df2)

is the above formulation sufficient to capture the repeated measures by
family?
Next, when I do this with lme4a, I get an error:

?Error in lmer(y ~ concordant + age.proband + age.other + sex.proband + ?:
? number of levels of each grouping factor must be less than number of obs

I have seen this thread:
http://permalink.gmane.org/gmane.comp.lang.r.lme4.devel/3313
but the change does not appear to be included in the latest lme4a
package from Rforge, is there another repo where this has been
incorporated? or is this an error on my part?


thanks,
-brent

concordant ?family_id ? external_ref.proband ? ?external_ref.other
sex.proband sex.other ? age.proband age.other ? y(fake)
T ? 58 ?80015550 ? ?80015543 ? ?M ? F ? 15 ?19 ?1
F ? 58 ?80015550 ? ?80016946 ? ?M ? F ? 15 ?8 ? 2
T ? 54 ?80015499 ? ?80015338 ? ?F ? F ? 5 ? 7 ? 3
F ? 54 ?80015499 ? ?80013112 ? ?F ? M ? 5 ? 13 ?4
F ? 22 ?80012269 ? ?80012252 ? ?F ? F ? 12 ?10 ?5
F ? 22 ?80012269 ? ?80018691 ? ?F ? M ? 12 ?8 ? 5