Measurement Equality of Frequency and Severity Item Response Options on Depression and Generalized Anxiety Scales

Rating scales are commonly used in psychological research and practice. It is important to consider how different item response options used on rating scales, such as those based on frequency or severity, may affect how they measure psychological constructs. In this study, participants were randomly assigned to conditions where they completed two depression and two generalized anxiety rating scales that used either frequency or severity item response options. Descriptive statistics and reliability estimates across depression and generalized anxiety scales using different item response options were similar. Measurement invariance tests indicated that depression and generalized anxiety scales with different item response options could be considered practically invariant. Finally, depression and generalized anxiety scales with different item response options had similar correlations with measures of impairment and other psychological constructs. There were essentially no differences in psychometric and measurement properties of these depression and generalized anxiety scales when using different item response options, suggesting this may not substantially affect the measurement of these constructs.