[R-sig-ME] GEE with gamma family and log link
t@h@|n|erdou@uo|c @end|ng |rom gm@||@com
Sat Nov 13 02:32:16 CET 2021
I am fitting a generalized estimating equation with gamma family and log
link. I am using GEE (geeglm function) from the R pcakage “geepack” with
gamma family and log link and unstructured correlation structure.
Here, response variable or outcome is IFN_gamma_protein_pg_mg . Exposure is
intervention or probiotic use. Another covariate is Timepoint.
My code and the output is as mentioned below.
I am trying to interpret the coefficients as follows:
For every one-unit increase in the probiotic across the population, the log
average of IFN_gamma_protein increases by 0.34 units.
The exponentiated coefficient ( exp )= (exp(0.34)=1.41) is the factor by
which the arithmetic mean outcome on the original scale multiplied, i.e.,
when intervention is probiotic, for every one-unit increase in the
probiotic across the population, the average of IFN_gamma_protein on the
original scale is 1.41 times higher compared to when intervention is
control within levels of other variable.
Similarly, for timepoint 2, the average of IFN_gamma_protein on the
original scale is exp( )= exp(0.99)= 2.69 times higher compared to
timepoint 1 within levels of other variable.
For time point 3, the average of IFN_gamma_protein on the original scale is
exp( )= exp(5.30)= 200.34 times higher compared to timepoint 1 within
levels of other variable.
Can someone confirm me that I am in the right track in the interpretation
I am posting here as I also want to fit a Gamma GLMM.
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