[R] Problems with glht function for lme object
anord
andreas.nord at zooekol.lu.se
Fri Jan 7 14:28:26 CET 2011
Dear all,
I'm trying to make multiple comparisons for an lme-object. The data is for
an experiment on parental work load in birds, in which adults at different
sites were induced to work at one of three levels ('treat'; H, M, L). The
response is 'feedings', which is a quantitative measure of nest provisioning
per parent per chick per hour. Site is included as a random effect (one
male/female pair per site).
My final model takes the following form:
feedings ~ treat + year + data^2, random = ~1|site,data=feed.df
For this model, I would like to do multiple comparisons on 'treat', using
the multcomp package:
summary(glht(m4.feed,linfct=mcp(treat="Tukey")))
However, this does not work, and I get the below error message.
Error in if (is.null(pkg) | pkg == "nlme") terms(formula(x)) else slot(x, :
argument is of length zero
Error in factor_contrasts(model) :
no ‘model.matrix’ method for ‘model’ found!
I suspect this might have quite a straightforward solution, but I'm stuck at
this point.
Any help would be most appreciated. Sample data below.
Kind regards,
Andreas Nord
Sweden
==============
feedings sex site treat year date^2
1.8877888 M 838 H 2009 81
1.9102787 M 247 H 2009 81
1.4647229 M 674 H 2010 121
1.4160590 M 7009 M 2009 144
1.3106749 M 863 M 2010 196
1.2718121 M 61 M 2009 225
1.2799263 M 729 L 2009 256
1.5829564 M 629 L 2009 256
1.4847251 M 299 L 2010 324
1.2463151 M 569 L 2010 324
2.1694169 F 838 H 2009 81
1.5966899 F 247 H 2009 81
2.4136983 F 674 H 2010 121
1.7784873 F 7009 M 2009 144
1.6681317 F 863 M 2010 196
2.3691275 F 61 M 2009 225
2.0672192 F 729 L 2009 256
1.6389902 F 629 L 2009 256
0.9307536 F 299 L 2010 324
1.6786767 F 569 L 2010 324
==============
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