Brendan It looks like you're working with the 2PL, what are you trying to estimate exactly? There are a lot of built in psychometric functions that you might consider using.
> -----Original Message----- > From: r-help-boun...@r-project.org > [mailto:r-help-boun...@r-project.org] On Behalf Of Brendan Morse > Sent: Monday, April 13, 2009 10:54 AM > To: r-help@r-project.org > Subject: [R] equation help > > Hi everyone, I am having a bit of trouble correctly > structuring an equation in R. > > > Here is the equation > > > > Here is what I thought > > for(i in 1:numItem)for(x in 1:numCat) > > Ptheta[,i,x]<-(exp(-1.702*a[i]*(theta-b[i,x+1])) > > My problem is that I am not sure how to get it to read the > equation as having two indexing points (i and x). Right now > it is trying to read it as a matrix, but each value (i and x) > are only vectors. Does anyone have any suggestions on how to > get R to recognize this? As an example, numItem may = 20 and > numCat may = 3 and I am trying to evaluate this over all > values of numCat for each value of numItem. > > Thanks, > Brendan > > ______________________________________________ > R-help@r-project.org 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. > ______________________________________________ R-help@r-project.org 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.
