[R-sig-ME] Offset() in gls() in nlme

ONKELINX, Thierry Thierry.ONKELINX at inbo.be
Wed Nov 12 09:52:11 CET 2014

Dear Mark,

In case of a linear model you can create a new variable Y = R - ssb and model Y without offset instead of R with ssb as offset. That should give the same parameter estimates.

Best regards,

ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature and Forest
team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance
Kliniekstraat 25
1070 Anderlecht
+ 32 2 525 02 51
+ 32 54 43 61 85
Thierry.Onkelinx op inbo.be

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-----Oorspronkelijk bericht-----
Van: r-sig-mixed-models-bounces op r-project.org [mailto:r-sig-mixed-models-bounces op r-project.org] Namens Mark Payne
Verzonden: dinsdag 11 november 2014 13:23
Aan: r-sig-mixed-models op r-project.org
Onderwerp: [R-sig-ME] Offset() in gls() in nlme


I am trying to use the following model formula in gls() in the nlme package:

R ~ Turb + offset(ssb)

Unfortunately, gls() seems to ignore the offset argument and give results that are identical to

R ~ Turb

This is not the case when I use lm() - however, I would like to include a
corAR1() term as well, which is why I am using gls().

Is this known and intended behaviour? If so, is there a recommended workaround/alternative?

Best wishes,


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