RESUMEN
BACKGROUND: When collecting data from human participants, it is often important to minimise the length of questionnaire-based measures. This makes it possible to ensure that the data collection is as engaging as possible, while it also reduces response burden, which may protect data quality. Brevity is especially important when assessing eating disorders and related phenomena, as minimising questions pertaining to shame-ridden, unpleasant experiences may in turn minimise any negative affect experienced whilst responding. METHODS: We relied on item response theory to shorten three eating disorder and body dysmorphia measures, while aiming to ensure that the information assessed by the scales remained as close to that assessed by the original scales as possible. We further tested measurement invariance, correlations among different versions of the same scales as well as different measures, and explored additional properties of each scale, including their internal consistency. Additionally, we explored the performance of the 3-item version of the modified Weight Bias Internalisation Scale and compared it to that of the 11-item version of the scale. RESULTS: We introduce a 5-item version of the Eating Disorder Examination Questionnaire, a 3-item version of the SCOFF questionnaire, and a 3-item version of the Dysmorphic Concern Questionnaire. The results revealed that, across a sample of UK adults (N = 987, ages 18-86, M = 45.21), the short scales had a reasonably good fit. Significant positive correlations between the longer and shorter versions of the scales and their significant positive, albeit somewhat weaker correlations to other, related measures support their convergent and discriminant validity. The results followed a similar pattern across the young adult subsample (N = 375, ages 18-39, M = 28.56). CONCLUSIONS: These results indicate that the short forms of the tested scales may perform similarly to the full versions.
This manuscript introduces short versions of existing measures of eating disorders and body dysmorphia, specifically the Eating Disorder Examination Questionnaire, the SCOFF Questionnaire, and the Dysmorphic Concern Questionnaire. We further investigate the properties of the recently introduced 3-item short version of the modified Weight Bias Internalisation Scale. Across analyses including measurement invariance testing and bivariate correlations aiming to assess convergent and discriminant validity, we find support that the short scales may perform similarly to their longer versions. These short scales may contribute in meaningful ways to research where the brevity of questionnaire-type measures may make a difference by contributing to data quality.
RESUMEN
It is often important to minimise the time participants in social science studies spend on completing questionnaire-based measures, reducing response burden, and increasing data quality. Here, we investigated the performance of the short versions of some widely used depression, anxiety, and psychological distress scales and compared them to the performance of longer versions of these scales (PHQ-2 vs PHQ-9, GAD-2 vs GAD-7, Malaise-3 vs Malaise-9, K6 vs K10). Across a sample of UK adults (N = 987, ages 18-86), we tested the existing factor structure and accuracy of the scales through confirmatory factor analyses and exploration of the total information functions, observing adequate model fit indices across the measures. Measurement invariance was tested across birth sex and age groups to explore whether any differences in measurement properties or measurement bias may exist, finding support for the invariance of most measures. We conducted bivariate correlations across the measures as a way of obtaining evidence of the equivalence in the rank-ordering of short vs long scales. The results followed a similar pattern across the young adult subsample (N = 375, ages 18-39) as in the overall sample. Overall, these results indicate that the short forms of the tested scales may perform similarly to the full versions. Where brevity is important, researchers may opt to use the shorter versions of the scales based on these data.