On 5/16/07, Rick DeShon <[EMAIL PROTECTED]> wrote: > Hi All. > > I'm trying to run a simple model from Baayan, Davidson, & Bates and getting > a confusing error message. Any ideas what I'm doing wrong here? > > # Here's the data..... > Subj <- factor(rep(1:3,each=6)) > Item <- factor(rep(1:3,6)) > SOA <- factor(rep(0:1,3,each=3)) > RT <- > c(466,520,502,475,494,490,516,566,577,491,544,526,484,529,539,470,511,528) > priming <- data.frame(cbind(Subj,Item,SOA,RT)) > > str(priming) > 'data.frame': 18 obs. of 4 variables: > $ Subj: num 1 1 1 1 1 1 2 2 2 2 ... > $ Item: num 1 2 3 1 2 3 1 2 3 1 ... > $ SOA : num 1 1 1 2 2 2 1 1 1 2 ... > $ RT : num 466 520 502 475 494 490 516 566 577 491 ... > > #Here's the call taken directly from the paper > priming.lmer1 <- lmer(RT ~ SOA + (1 | Item) + (1 | Subj), data = priming) > > #Here's the error.... > Error in rbind(Item = <S4 object of class "dgCMatrix">, Subj = <S4 object of > class "dgCMatrix">) : > cannot coerce type S4 to list vector > > Any idea what I'm doing wrong? > > > sessionInfo() > R version 2.5.0 (2007-04-23) > i386-pc-mingw32 > other attached packages: > lme4 Matrix lattice nlme > "0.9975-13" "0.99875-1" "0.15-4" "3.1-80"
It's a version skew problem (and thanks for including the sessionInfo() output that makes it possible to detect this). Changes were made in version 0.99875-0 and later of the Matrix package that require a new version of the lme4 package. Please install version 0.99875-0 or later of lme4. However, while we are discussing this example, notice that using the cbind inside the call to data.frame causes the factors to become numeric variables. That is undesirable. In this case it is benign but it could be harmful. A better approach is simply to give the variables and their names in the call data.frame. Also, the sequence factor(rep(...)) can be written better as a call to the underutilized function gl. > priming <- data.frame(Subj = gl(3,6), Item = gl(3,1,18), SOA = > gl(2,3,18,labels = 0:1), + RT = c(466,520,502,475,494,490,516,566,577,491,544,526,484,529,539,470,511,528)) > str(priming) 'data.frame': 18 obs. of 4 variables: $ Subj: Factor w/ 3 levels "1","2","3": 1 1 1 1 1 1 2 2 2 2 ... $ Item: Factor w/ 3 levels "1","2","3": 1 2 3 1 2 3 1 2 3 1 ... $ SOA : Factor w/ 2 levels "0","1": 1 1 1 2 2 2 1 1 1 2 ... $ RT : num 466 520 502 475 494 490 516 566 577 491 ... > lmer2(RT ~ SOA + (1|Subj) + (1|Item), priming) Linear mixed-effects model fit by REML Formula: RT ~ SOA + (1 | Subj) + (1 | Item) Data: priming AIC BIC logLik MLdeviance REMLdeviance 149.4 153 -70.72 154.4 141.4 Random effects: Groups Name Variance Std.Dev. Subj (Intercept) 499.37 22.347 Item (Intercept) 607.80 24.654 Residual 137.35 11.719 Number of obs: 18, groups: Subj, 3; Item, 3 Fixed effects: Estimate Std. Error t value (Intercept) 522.111 19.604 26.633 SOA1 -18.889 5.525 -3.419 Correlation of Fixed Effects: (Intr) SOA1 -0.141 ______________________________________________ R-help@stat.math.ethz.ch mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.