Scaling attitude items constructed and scored in the likert tradition

The statement scaling emphasis associated with the Thurstone tradition for the study of attitude provides no direct consequence for attitude measurement, while conversely, the attitude measurement emphasis in the Likert tradition provides no direct consequence for statement scaling. Both aspects of the study of attitude are unified by a generalisation of Rasch's simple logistic model for dichotomously scored achievement items. The generalized model caters for the response category system of attitude questionnaires constructed and scored in the Likert tradition, but because both statements and persons are parameterised, the model has consequences for both statement scaling and person measurement. As with the simple logistic model, the two sets of parameter estimates, in this case those of the statements and of the persons, are independent of each other. An illustration involving attitudes to the professional roles of teachers is provided.