Date created: | Last Updated:

Category: Project

Description: More and more researchers use Ecological Momentary Assessment (EMA) to answer research questions about psychological processes in daily life, for example how well-being changes across the day. However, research on valid state measures is lagging behind. Only a few instruments have been developed and validated to specifically assess states in EMA studies. Oftentimes, researchers create their own items or adapt existing trait instruments to capture momentary experiences, but do not evaluate their psychometric properties, which leaves the statistical inferences questionable. We present a three-step procedure to facilitate the development of state measures. The first step comprises the definition of the measured construct, intended purpose, and targeted population. In the second step, a candidate pool of items and the response options are generated. In the third step, the psychometric properties of the items are evaluated. Specifically, we describe how to select well-performing items by tailoring a brute-force algorithm to optimize different criteria simultaneously. We further draw attention to important measurement topics such as planned missingness designs and longitudinal measurement invariance. The three steps are illustrated by means of an empirical example, where we execute and document the full procedure to develop a new instrument to measure well-being in everyday life.