CHOICE MODEL ANALYSIS OF THE PICK ANY N TYPE OF BINARY DATA/

In the ''pick any/n'' method, subjects are asked to choose any number of items from a list of n items according to some criterion. This kind of data can be analyzed as a special case of either multiple-choice d ata or successive categories data where the number of response categor ies is limited to two. An item response model was proposed for the lat ter case, which is a combination of an unfolding model and a choice mo del. The marginal maximum-likelihood estimation method was developed f or parameter estimation to avoid incidental parameters, and an expecta tion-maximization algorithm used for numerical optimization. Two examp les of analysis are given to illustrate the proposed method, which we call MAXSC.