Running examples in 'psychotools-Ex.R' failed
The error most likely occurred in:

> ### Name: pcmodel
> ### Title: Partial Credit Model Fitting Function
> ### Aliases: pcmodel PCModel.fit print.pcmodel summary.pcmodel
> ###   print.summary.pcmodel coef.pcmodel bread.pcmodel estfun.pcmodel
> ###   logLik.pcmodel vcov.pcmodel
> ### Keywords: regression
> 
> ### ** Examples
> 
> o <- options(digits = 4)
> 
> ## Verbal aggression data
> data("VerbalAggression", package = "psychotools")
> 
> ## Partial credit model for the other-to-blame situations
> pcm <- pcmodel(VerbalAggression$resp[, 1:12])
> summary(pcm)

Partial credit model

Item category parameters:
               Estimate Std. Error z value Pr(>|z|)
S1WantCurse-C2    -1.52         NA      NA       NA
S1DoCurse-C1     -19.04         NA      NA       NA
S1DoCurse-C2       1.44         NA      NA       NA
S1WantScold-C1   -16.15         NA      NA       NA
S1WantScold-C2     5.59         NA      NA       NA
S1DoScold-C1     -17.56         NA      NA       NA
S1DoScold-C2      10.11         NA      NA       NA
S1WantShout-C1   -16.66         NA      NA       NA
S1WantShout-C2    13.91         NA      NA       NA
S1DoShout-C1      -8.35         NA      NA       NA
S1DoShout-C2      18.56         NA      NA       NA
S2WantCurse-C1   -17.84         NA      NA       NA
S2WantCurse-C2    -3.48         NA      NA       NA
S2DoCurse-C1     -17.85         NA      NA       NA
S2DoCurse-C2       3.58         NA      NA       NA
S2WantScold-C1   -17.29         NA      NA       NA
S2WantScold-C2     5.02         NA      NA       NA
S2DoScold-C1     -15.34         NA      NA       NA
S2DoScold-C2      14.51         NA      NA       NA
S2WantShout-C1   -14.80         NA      NA       NA
S2WantShout-C2    12.82         NA      NA       NA
S2DoShout-C1      -3.32         NA      NA       NA
S2DoShout-C2      19.08         NA      NA       NA

Log-likelihood: -22800 (df = 23) 
Number of iterations in BFGS optimization: 2 

> 
> ## visualizations
> plot(pcm, type = "profile")
> plot(pcm, type = "regions")
> plot(pcm, type = "curves")
> plot(pcm, type = "information")
> plot(pcm, type = "piplot")
Error in uniroot(function(pp) rawscore - sum(ojv * exp(ojv * pp - unlist(tp))/unlist(sapply(1:m,  : 
  f() values at end points not of opposite sign
Calls: plot ... personpar.pcmodel -> sapply -> lapply -> FUN -> uniroot
Execution halted