Dear list I am calling the functiton bugs() provided by R2WinBugs to performs an IRT analysis. The function returns a set of estimated parameters over n replications/iterations. For each replication, two sets of person measures (theta1 and theta2) and two sets of item difficulty parameters (diff1 and diff2) are returned. The code used to obtain these estimates is as follows:
sim <- bugs(data,init,model.file="drift.bugs",parameters=c("theta1","theta2","diff1","diff2"),n.chains=n.chains,n.iter=n.reps,n.burnin=1000,bin=1,n.thin=1,digits=3, codaPkg=T) sim.list <- read.bugs(sim) However, when I read the coda files using read.bugs the order of the columns in the parameter matrix are as follows: [1] "deviance" "diff1[1]" "diff1[10]" "diff1[100]" "diff1[11]" "diff1[12]" "diff1[13]" [8] "diff1[14]" "diff1[15]" "diff1[16]" "diff1[17]" "diff1[18]" "diff1[19]" "diff1[2]" ... ... .............................................................. "diff2[10]" "diff2[100]" "diff2[11]" [106] "diff2[12]" "diff2[13]" "diff2[14]" "diff2[15]" "diff2[16]" "diff2[17]" "diff2[18]" [113] "diff2[19]" "diff2[2]" "diff2[20]" "diff2[21]" "diff2[22]" "diff2[23]" "diff2[24]" ... ... ............................................................................. "theta1[1]" "theta1[10]" [204] "theta1[100]" "theta1[101]" "theta1[102]" "theta1[103]" "theta1[104]" "theta1[105]" "theta1[106]" [211] "theta1[107]" "theta1[108]" "theta1[109]" "theta1[11]" "theta1[110]" "theta1[111]" "theta1[112]" The columns, in other words, are not in numerical order according to the index of the item difficulty or person measure parameter. Rather they appear to be in text-sorted order (e.g., 1, 10, 100...). Any ideas as to what might be going on? Thanks Barth PRIVILEGED AND CONFIDENTIAL INFORMATION This transmittal and any attachments may contain PRIVILEGED AND CONFIDENTIAL information and is intended only for the use of the addressee. If you are not the designated recipient, or an employee or agent authorized to deliver such transmittals to the designated recipient, you are hereby notified that any dissemination, copying or publication of this transmittal is strictly prohibited. If you have received this transmittal in error, please notify us immediately by replying to the sender and delete this copy from your system. You may also call us at (309) 827-6026 for assistance. ______________________________________________ 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.