The impact of item order on the factor structure of the PTSD Checklist for DSM‐5

The PTSD Checklist for DSM‐5 (PCL‐5) is the most widely used self‐report measure of posttraumatic stress disorder (PTSD) and is frequently modeled as having four correlated factors consistent with the DSM‐5 symptom structure. Some researchers have argued that item order may influence factor structure. Although two studies have examined this, they were both based on DSM‐IV criteria, and neither utilized a randomized design. Thus, this study aimed to determine whether item order impacts the factor structure of the PCL‐5, using two independent samples of community participants ( N = 347, 67.7% female, 85.3% White) and veterans ( N = 409, 83.6% male, 61.9% Black/African American). Approximately half of each sample was randomized to receive the PCL‐5 in the original fixed order, whereas the other half received a uniquely randomized version. We compared the DSM‐5 four‐factor model to several theoretically relevant models and found improved model fit in the seven‐factor hybrid model, community sample: ∆χ 2 = 153.87, p < .001; veterans: ∆χ 2 = 152.61, p < . 001. Consequently, the DSM‐5 four‐factor and seven‐factor hybrid models were retained for invariance testing. Across both samples, measurement invariance was examined between the randomized and fixed‐order groups. Configural invariance, partial metric invariance, and partial scalar invariance were achieved in both samples, p s = .054–.822, suggesting that the fit of the DSM‐5 four‐factor structure and the seven‐factor hybrid model, as measured using the PCL‐5, are not due to order effects. These findings support the continued use of the PCL‐5 in a fixed fashion.