Establishing Construct Continua in Construct Validation: The Process of Continuum Specification

Many areas of psychological science rely heavily on theoretical constructs, such as personality traits, attitudes, and emotions, and many of these measured constructs are defined by a continuum that represents the different degrees of the attribute. However, these continua are not usually considered by psychologists during the process of scale development and validation. Unfortunately, this can lead to numerous scientific problems, such as incomplete measurement of the construct, difficulties in distinguishing between constructs, and compromised evidence for validity. The purpose of the current article is to propose an approach for carefully considering these issues in psychological measurement. This approach, which we term continuum specification, is a two-stage process in which the researcher defines and then properly operationalizes the target continuum. Defining the continuum involves specifying its polarity (i.e., the meaning of its poles, or ends) and the nature of its gradations (i.e., the quality that separates high from low scores). Operationalizing the continuum means using this definition to develop a measure that (a) sufficiently captures the entire continuum, (b) has appropriate response options, (c) uses correct procedures for assessing dimensionality, and (d) accounts for the underlying response process. These issues have significant implications for psychological measurement.