Psychometric properties and rasch validation of the Herth Hope Index in a sample of Portuguese higher education students during a pandemic

A greater understanding of health-promoting factors, such as hope, is crucial for preventing and enhancing the mental health of higher education students. The Herth Hope Index (HHI) is a 12-item tool that has been widely used to assess a comprehensive, non-temporal perception of hope. While this instrument has been used extensively in adult populations, most studies focus on clinical populations. Additionally, the HHI reveals inconsistencies in terms of scale dimensionality and items to be retained. Therefore, this study sought to assess the HHI's psychometric characteristics in a sample of Portuguese Higher Education students. The person response validity, internal scale validity, unidimensionality, and uniform differential item functioning were assessed using a Rasch rating scale model. A total of 2227 higher education students participated during the e-survey activation period (spring semester of 2020). The mean age of the sample was 22.5 +/- 6.2 years (range 18-59 years). Three of the twelve items (#3, #5, and #6) failed to satisfy the established criterion for goodness of fit. Following the elimination of these three items, the resultant nine-item scale exhibited satisfactory item fit to the model, appropriate unidimensionality (52.4% of the variance explained), enough person goodness of fit, sufficient separation, and the absence of differential item functioning. The 9-item version of the HHI had psychometric properties comparable to the original 12-item version. This study also underscores the importance of validated instruments for assessing hope-based interventions in academic contexts. Further research is necessary to explore the potential dimensions inherent to the hope concept and to identify variations in hope profiles among items influenced by cultural attributes.