Measuring Change With Multiple Visual Analog Scales

Although the visual analog scale (VAS) may be useful for measuring change on subjective and potentially transient phenomena, there is concern about the reliability and construct validity of the associated measurement variables. The present study reports evidence for tau-equivalence of change scores associated with VASs designed for assessing tense arousal with synonymous indicators. This psychometric property allows an estimation of the true-score structure of the cross-sectional measurement variables in a longitudinal SEM model, including method effects. Findings suggest that VASs associated with synonymous indicators may yield highly reliable measurement variables. However, imperfect dynamic bipolarity was observed when data based on antonymous indicators were introduced into the analyses, a rather puzzling effect that deserves further elaboration.