Measurement Reactivity in Ecological Momentary Assessment Studies of Movement-Related Behaviors

Measurement reactivity has implications for behavioral science, as it is crucial to determine whether changes in constructs of interest represent true change or are an artifact of assessment. This study investigated whether measurement reactivity occurs for movement-related behaviors, motivational antecedents of behavior, and associations between them. Data from ecological momentary assessment studies of older adults ( n = 195) and women in midlife ( n = 75) lasting 8–10 days with 5–6 prompts/day and ambulatory monitoring of movement were used for this secondary data analysis. To examine potential drop-off patterns indicative of measurement reactivity, multilevel models tested whether behavior, antecedents, and associations changed after the first or first 2 prompts compared with remaining prompts and the first, first 2, or first 3 days compared with remaining days. Older adults’ sedentary behavior was lower, and time spent upright and intentions and self-efficacy to stand/move were higher on the first 2 and first 3 days compared with remaining days. Associations between intentions and self-efficacy and subsequent sedentary behavior were weaker earlier in the study compared to later. For women in midlife, light physical activity was higher at the first and first 2 prompts compared with remaining prompts, and physical activity motivation was higher across all prompts and days tested. There was a stronger association between intended and observed minutes of moderate to vigorous physical activity on the first 2 days compared with remaining days. Measurement reactivity appeared as expected for movement-related behaviors and motivational antecedents, though changes in associations between these constructs are likely do not reflect measurement reactivity.