search for: irtoy

A new version of irtoys is / will be available on CRAN. Two minor bugs have been fixed. One of these is more interesting: the previous code did not anticipate negative estimates for discriminations. What I did not know is that, unlike ICL or Bilog, ltm does not constrain discriminations to be positive. This means that it...

A new version of irtoys is / will be available on CRAN. Two minor bugs have been fixed. One of these is more interesting: the previous code did not anticipate negative estimates for discriminations. What I did not know is that, unlike ICL or Bilog, ltm does not constrain discriminations to be positive. This means that it...

I have just submitted irtoys_0.1.0, a package potentially useful for those working with IRT models. It can fit the 1PL, 2PL, and 3PL models through a simple and unified syntax, using either the R package ltm, Brad Hanson's ICL program, or the commercially available BILOG-MG. The purpose is basically to facilitate teac...

I have just submitted irtoys_0.1.0, a package potentially useful for those working with IRT models. It can fit the 1PL, 2PL, and 3PL models through a simple and unified syntax, using either the R package ltm, Brad Hanson's ICL program, or the commercially available BILOG-MG. The purpose is basically to facilitate teac...

Hello All, I am trying to subset a matrix using subset() and it works fine when I use matrix notation, but doesn't work when I use established column names. Sample code is below: library(mvtnorm) library(sm) library(ltm) library(irtoys) k<- 100 set.seed(271828) t <- rmvnorm(n=k,mean=c(-1,0,1),sigma=matrix(c(1,.8,.5,.8,1,.8,.5,.8,1),3,3)) colMeans(t) var(t) pairs(t) #tview <-edit(t) t1<-as.matrix(t[,1]) t2<-as.matrix(t[,2]) t3<-as.matrix(t[,3]) # write.table(t, file = "c:/ability.dat", sep = &quo...

...ue. This value is compared to a random uniform value, and is coded a 1 if the function is greater than the uniform value, 0 if it is <= to the uniform value. My code thus far works great, but I just need it to run several times. Here we go: library(mvtnorm) library(sm) library(ltm) library(irtoys) k<- 5000 set.seed(271828) t <- rmvnorm(n=k,mean=c(-1,0,1),sigma=matrix(c(1,.8,.5,.8,1,.8,.5,.8,1),3,3)) #Using mv here because of the likely association of ability (theta = t) across time. t1<-as.matrix(t[,1]) t2<-as.matrix(t[,2]) t3<-as.matrix(t[,3]) set.seed(271828) # Pop...

Is there some reason why > (1:2)+(1:3) [1] 2 4 4 Warning message: In (1:2) + (1:3) : longer object length is not a multiple of shorter object length can't be made into an error? I realise it was there in S-PLUS, but since it produces a warning there can't be many examples on CRAN or Bioconductor using it, and I can't think of any situation where it would be used deliberately.

CRAN (and crantastic) updates this week New packages ------------ * bdoc (1.0) Michael Anderson http://crantastic.org/packages/bdoc This package contains a function that will classify DNA barcodes as well as a few test and reference data sets. * bdsmatrix (1.0) Terry Therneau http://crantastic.org/packages/bdsmatrix This is a special case of sparse matrices, used by coxme and