Reliability and validity of the Thai "Global Person Generated Index", an individualised measure of quality of life

The “Global Person Generated Index” (GPGI) is an individualised measure of global quality of life (QoL). Individualised measures have been used within a health context, however until recently have been rarely used to explore global QoL. This paper establishes the GPGI’s validity and reliability in Thailand. Data were collected from participants in two sites in Northeast Thailand. Participants completed the Thai GPGI, the “Satisfaction with Life Scale”(SWLS), a modified “Positive and Negative Affect Scale” (PANAS) and provided demographic data. 81 participants provided data at T1. 70 participants completed data for test-retest (two week interval) reliability comparisons. Test-retest reliability correlation was 0.678 (p < 0.001) for participants reporting no change in QoL. GPGI correlated moderately with SWLS (0.381, p < 0.01) and PANAS scales (0.291 and −0.378, both p < 0.01), indicating validity. GPGI scores were related to health and correlated to a moderate degree with income (0.379, p < 0.05). GPGI scores did not show the expected differences in scores based on gender, although this may be owing to cultural issues. Areas nominated as important to QoL included family, money, house, health and employment, which mirrors items on other QoL scales and previous work with individualised measures. The Thai GPGI is reliable for group comparisons and valid. The difficulties of designing cross-cultural construct validity hypotheses are acknowledged. Areas nominated as important to QoL were diverse and largely asset based. The GPGI is recommended for use to explore global QoL and potentially useful for needs assessment and exploration of response shift