Approaches to personality inventory construction: A comparison of merits.

The three major approaches to personality scale construction, the external, inductive, and deductive strategies, are discussed and their rationales compared. It is suggested that all scales should possess validity, communicability, and economy. The relative importance of these characteristics, however, varies with the purpose for which the instrument is being constructed. A review of more than a dozen comparative studies revealed no consistent superiority of any strategy in terms of validity or predictive effectiveness. But deductive scales normally communicate information more directly to an assessor, and they are definitely more economical to build and to administer. Thus, wherever there is a genuine choice, the simple deductive approach is recommended. Furthermore, self-rating scales narrowly but consistently outdo questionnaire scales in terms of validity and are clearly superior in terms of communicability and economy. There may not be many situations in which the widespread preference for questionnaires is justified. It is concluded that the more commonsensical approaches to personality measurement have a lot to offer. Anyone who is bold enough today to develop a general-purpose personality inventory has basically three options for how to go about it. They are the external approach (also called empirical, or criterion group), the inductive approach (also called internal, internal consistency, or itemetric), and the deductive approach (also called rational, intuitive, or theoretical). This article reviews their respective merits on both a priori and empirical grounds. For clarity's sake I will exaggerate the differences between the philosophies associated with these three approaches.