[R-sig-ME] offset in lme4

[Eleni Sofianopoulou]

Hello all

I have problem to use the offset in lme4 successfully. When I add the offset in my model it seems that it has no effect on the output. The models with and without the offset seem to produce the same results.

I have tried 2 different ways to add the offset on the model but I think the code I use is correct. I wonder whether anyone has an idea why this is and if can save me at this point.


Model A with offset:
>slb21offset<-lmer(log(slb+1)~pmavg0+trafsum0+conmonth+INC+EMP+EDU+(1|GP
>), offset=(logoffset_slb), slb21R)

Model B with offset:
slb21offsetb<-lmer(log(slb+1)~pmavg0+trafsum0+conmonth+INC+EMP+EDU+yrreg+offset(logoffset_slb)+(1|GP), slb21R)

Model without offset:
slb21<-lmer(log(slb+1)~pmavg0+trafsum0+conmonth+INC+EMP+EDU+(1|GP), slb21R)

I attach a file with my data.

Many thanks
Eleni

Eleni Sofianopoulou
Institute of Health and Society,
Newcastle University
William Leech Building
NE2 4HH
Tel:+44(0)191 246 4840