Permanency and ephemerality of psychological measures with application to organizational commitment.

The constancy or change of an attribute is important to most substantive areas of psychology. During the past decade, 2 independent methodological schools have developed statistical models for the depiction of longitudinal research. One, which might be called the European school, has created latent state-trait models. Alternatively, the American school has formulated models that go by the rubric of latent curve analysis or latent growth models. In this article, the authors integrate both approaches into a detailed unified latent curve and latent state-trait model (LC-LSTM) that includes the significant features from both schools. From the LC-LSTM framework, the permanency and ephemerality of psychological measures are discussed and the concepts of stability and reliability are reformulated. In addition, a comprehensive illustration on organization commitment is presented.