Measuring Perceived Social Support After Disaster: Development and Validation of the Perceived Social Support in Disasters Scale (PSSDS-28)

Background/Objectives: Measuring perceived social support after disaster remains an unresolved psychometric problem. Most instruments do not jointly capture the source of support (from whom it comes) and its function (how it operates). None has been validated in a disaster-survivor sample with retrospectively framed items. We developed and validated the Perceived Social Support in Disasters Scale (PSSDS-28), a 28-item measure integrating both dimensions. Methods: In Phase 1, a PRISMA 2020-guided systematic review; a two-round Delphi with eight experts, cognitive interviews (n = 12); and a pilot study (N = 150) produced a 31-item form. In Phase 2, face-to-face data were collected from 607 adults affected by the 6 February 2023 Kahramanmaraş earthquakes (Türkiye). Multiple analytic frameworks converged on a five-factor, 28-item structure comprising family–relative, social environment, institutional, emotional, and instrumental–informational support. Results: The correlated five-factor model fit the independent validation sample well (CFI = 0.954, RMSEA = 0.076, and SRMR = 0.072) and outperformed a one-factor alternative (ΔCFI = 0.222). Blocks showed strong internal consistency (ordinal α = 0.852–0.949), composite reliability (0.865–0.950), and adequate test–retest stability (ICC = 0.542–0.909). Scalar measurement invariance held across six groupings, with no meaningful differential item functioning. Convergent and discriminant evidence supported construct validity, and common-method variance was negligible. Institutional (M = 3.29) and instrumental–informational support (M = 2.99) scored lowest—a profile a global score would conceal. Conclusions: The PSSDS-28 provides promising initial psychometric evidence for a multidimensional post-disaster assessment instrument situated at the perceived–received interface, a target that general-purpose scales are not designed to capture. Criterion-related validity, cross-cultural validity, and cross-disaster replicability remain to be demonstrated.