[R-sig-ME] Lmer model drops one parameter

[Pierre Marle]

Dear everyone,

I have a lmer model to predict [Hg] according to a categorical variable (7 parameters for 134 observations) as fixed effects and the species as random effect.

The issue that I have is that the summary of model dropped one parameter of the qualitative variable. This is not a problem of unsufficient data of the dropped parameter because it has a high number of observations comparing with other parameters. Moreover, I don’t have any warning message after the model processing.

lme <- lmer(Hg ~ Feeding_type + (1|Sp), data=sp, REML=T)

Fixed effects:
                                             Estimate    Std. Error       df t value Pr(>|t|)
(Intercept)                              0.08404    0.01344 28.13392   6.254 9.06e-07 ***
Feeding_typeGatherer          -0.06692    0.02261 27.57559  -2.960  0.00626 **
Feeding_typeGrazer             -0.06701    0.02084 20.31009  -3.216  0.00427 **
Feeding_typePiercer             -0.07752    0.03093 18.71971  -2.506  0.02161 *
Feeding_typePredator           -0.03889    0.02026 25.21664  -1.919  0.06634 .
Feeding_typeShredder          -0.04154    0.01722 27.41420  -2.413  0.02278 *
Feeding_typeSponge-feeder  0.01674    0.02157 23.04972   0.776  0.44566

As you can see I’m using the lme4 package with REML=T. Should I change something to have the coefficients of all the feeding types in the summary?

I will be very grateful if someone could help me.

Kind regards

Pierre Marle
Phd student / Research assistant
pierre.marle using unige.ch<mailto:pierre.marle using unige.ch> / +41 22 379 0487

Département F.-A. Forel des sciences de l’environnement et de l'eau
Laboratoire d’Ecologie et de Biologie Aquatique
Sciences de la Terre et de l’Environnement
Université de Genève

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