In Coombs' unidimensional unfolding theory each individual ranks all stimuli, often in terms of preference judgments. These ranks, called I scales, are used to infer the latent continuum called a J scale which is presumed to have generated the I scale rankings. A major problem concerns the inference of the J scale given a set of I scales because an I scale is not unique to any one J scale. This paper presents a procedure for estimating J scale probabilities given a set of I scales. Models for three and four or more stimuli are presented. Results of computer tests are reported.