I’m seeking to design a MaxDiff experiment that will have a number of blocks of this type:
Which of these items is the most important? Which of these items is the least important? Item 1 Item 2 Item 3 Item 4 I’m seeking to use the choiceDes package <http://cran.r-project.org/web/packages/choiceDes/choiceDes.pdf> to design the experiment. The relevant function is tradeoff.des. Usage: tradeoff.des(items, shown, vers, tasks, fname=NULL, Rd=20, Rc=NULL, print=TRUE) I believe I understand the items, shown and vers parameters: items: number of total items in the experiment show: number of items shown per block vers: number of blocks ...but I’m not quite sure what the tasks parameter is yet. For example, let’s say I have 20 items total in the study. I want to show 4 items per block, with 10 blocks total. I enter: tempDes <- tradeoff.des(20, 4, 10, 2, "tempDesign.txt", 20, NULL, TRUE) …hoping that the 2 is the number of questions (most important/least important) per block. I get an error: Error in optBlock(~., des.d, rep(tasks, vers), nRepeats = Rd) : The number of withinData rows is not large enough to support the blocked model. If I put the number of blocks up to 50: tempDes <- tradeoff.des(20, 4, 50, 2, "tempDesign.txt", 20, NULL, TRUE) …I get the same error. What is the correct way to use choiceDes to design a MaxDiff experiment of this kind? Thanks very much in advance to all for any thoughts or info! Best, -Vik [[alternative HTML version deleted]] ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
