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

[Michael Kubovy]

Dear r-helpers,

Can anyone suggest why lm() doesn't complain here:

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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