zhongmiao wang zhongmiao at gmail.com writes:
I am studying the effect of schools on student achievement growth over
time. School effect is random. The effects of schools in prior years
are assumed to be persistent till the current year. Thus, the total
school effect in the second year is like J=J2+J1. Does anyone know how
to model this kind of cumulating random effects in lmer? Thanks in
advance!
Compute new variables with the cumulative effect of the previous years and use
these instead of J2, J1. If there are not too many years, using reshape to
make a wide version of the data frame, and then adding up within a row is
probably the most transparent way to do this.
Dieter
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