A procedure for evaluating sensitivity to within-person change: can mood measures in diary studies detect change reliably?

Abstract

The recent growth in diary and experience sampling research has increased research attention on how people change over time in natural settings. Often however, the measures in these studies were originally developed for studying between-person differences, and their sensitivity to within-person changes is usually unknown. Using a Generalizability Theory framework, the authors illustrate a procedure for developing reliable measures of change using a version of the Profile of Mood States (POMS; McNair, Lorr, & Droppleman, 1992) shortened for diary studies. Analyzing two data sets, one composed of 35 daily reports from 68 persons experiencing a stressful examination and another composed of daily reports from 164 persons over a typical 28-day period, we demonstrate that three-item measures of anxious mood, depressed mood, anger, fatigue, and vigor have appropriate reliability to detect within-person change processes.

Figure 1. Trajectories of moods over 35 days among bar examinees

NOTE: The bar examination fell on Days 31 and 32, as indicated by the dashed vertical lines. Saturdays and Sundays fell on Days 6 and 7, Days 13 and 14, Days 20 and 21, Days 27 and 28, and Days 34 and 35, as indicated by the solid vertical lines.

Figure 2. Trajectories of moods over 28 days among graduate students

NOTE: Saturdays and Sundays fell on Days 6 and 7, Days 13 and 14, Days 20 and 21, and Days 27 and 28, as indicated by the solid vertical lines.