A Multinational Quasi-Experimental Evaluation of a Digital Positive Psychology Intervention for University Students' Well-Being and Optimism

This multinational quasi-experimental study examined pre–post changes associated with a digitally supported positive psychology intervention implemented across five European higher education institutions. The final analytical sample comprised 548 students, including 389 participants in the intervention group and 159 in the control group. Quality of life, dispositional optimism, depressive symptoms, and grit were assessed using the WHOQOL-BREF, LOT-R, CES-D, and Grit-S, respectively. Baseline comparisons identified significant differences between groups in age, optimism, and depressive symptoms. No statistically significant pre–post changes were observed in the control group. In the intervention group, significant increases were observed in physical quality of life (p = .028), psychological quality of life (p = .011), and dispositional optimism (p < .001), whereas changes in social relationships, environmental quality of life, grit, and depressive symptoms were not statistically significant. Substantial differences were also observed across participating institutions. These findings indicate favourable within-group changes in selected outcomes among intervention participants. However, because the available analyses do not include an adjusted group-by-time interaction, the results should not be interpreted as establishing a causal intervention effect. Further research using adjusted longitudinal models and randomised designs is warranted.