[R] Why does lmList() fail when lm() doesn't?

[Petr Klasterecky]

Michael Kubovy napsal(a):
> Dear r-helpers,
> 
> Can anyone suggest why lm() doesn't complain here:

No, we can't since we don't have your data and we have no idea what 
logOdds, task and osss are...

The error given below says you are trying to model the effect of a 
factor, which however only has 1 level. So maybe lm() didn't treat your 
variable(s) as factor(s) while lmList does?

Petr

> 
> summary(osss.lm1 <- lm(logOdds ~ c.setSize %in% task, data = osss))
> 
> whereas in package:nlme (and in package:lme4)
> 
> osss.lmL <- lmList(logOdds ~ c.setSize %in% task | subj, data = osss)
> # Error in `contrasts<-`(`*tmp*`, value = "contr.treatment") :
> #	contrasts can be applied only to factors with 2 or more levels
> 
> If it were because for each subj I have only 1 datum per cell:
> 
> with(subset(osss, osss$subj == '42'), table(setSize, task))
> #       task
> # setSize os ss
> #      2  1  1
> #      3  1  1
> #      4  1  1
> #      5  1  1
> #      6  1  0
> #      7  1  0
> 
> then
> 
> osss.lm1 <- lm(logOdds ~ c.setSize %in% task, data = subset(osss, osss 
> $subj == '42'))
> 
> should fail as well, but I get
> 
> anova(osss.lm1)
> # Analysis of Variance Table
> #
> # Response: logOdds
> #                Df  Sum Sq Mean Sq F value Pr(>F)
> # c.setSize:task  2  6.8269  3.4134  1.9976 0.2059
> # Residuals       7 11.9612  1.7087
> 
> 
> _____________________________
> Professor Michael Kubovy
> University of Virginia
> Department of Psychology
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-- 
Petr Klasterecky
Dept. of Probability and Statistics
Charles University in Prague
Czech Republic