Studying Within-Person Changes in Work Motivation in the Short and MediumTerm: You Will Likely Need More Measurement Points than You Think!

Within-person analysis of data from longitudinal designs has become popular in the field. However, important characteristics of the design can influence that variability. In this paper, we examine how the number of measurement points obtained per participant influences in the within-person variance in work motivation. Using two sources of evidence (a systematic review and an empirical study) we show how the number of assessments substantially influences the amount of within-person variance reaching values of 52%-54% of total variance. We found that a minimum of 25-30 measurement points per participant is required to be rigorous.