Application of a Psychometric Rating Model to Ordered Categories Which Are Scored with Successive Integers

A latent trait measurement model in which ordered response categories are both parameterized and scored with successive integers is investigated and applied to a summated rating or Likert ques tionnaire. In addition to each category, each item of the questionnaire and each subject are para meterized in the model; and maximum likelihood estimates for these parameters are derived. Among the features of the model which make it attractive for applications to Likert questionnaires is that the total score is a sufficient statistic for a subject's at titude measure. Thus, the model provides a formal ization of a familiar and practical procedure for measuring attitudes.