Testing a Revised Measure of Public Service Motivation: Reflective versus Formative Specification

Public service motivation (PSM) is perceived as a multidimensional construct, as an overall, unobserved latent variable with various latent dimensions. The present study focuses on the relationships between PSM and its dimensions. The purposes in this study are to confirm a set of revised items as indicators of a rational base of PSM, to compare a four-factor model with various three-factor models, and to analyze whether PSM is defined as a formative or a reflective measurement model. Using survey data from 2,497 firefighters and a revised 12-item measure of PSM, this study shows that the revised items to measure the dimension of attraction to policy making are more appropriate for representing the rational base of PSM and that the original four-factor model is superior to any three-factor models. Based on the discussions about formative and reflective specification and the test results, this study provides theoretical and empirical evidence in support of a second-order, formative approach that PSM is an aggregate construct, meaning that it is a composite of its four dimensions. It also shows that it is necessary to develop more appropriate items for some dimensions of PSM. The practical implications are discussed.