Rasch analysis of the Meaning in Life Questionnaire among adults from South Africa, Australia, and New Zealand

BACKGROUND Meaning in life is a key indicator of subjective well-being and quality of life. Further developments in understanding and enhancing the construct will depend inter alia on the sound measurement thereof. This study is at the forefront of applying modern psychometric techniques to the Meaning in Life Questionnaire, a scale widely used to assess meaning in life. METHOD The Rasch rating scale model was applied to the Presence and Search subscales of the Meaning in Life Questionnaire using a sample of 601 adults from South Africa, Australia, and New Zealand. RESULTS The Presence subscale was insensitive at high levels of presence of meaning while the majority of the respondents fell in that range. Removal of item 9 ("My life has no clear purpose") and collapsing the response categories indicative of low and medium levels of the latent construct significantly improved the subscale's targeting and fit to the Rasch model, resulting in a subscale that exhibited differential item functioning on items 1 ("I understand my life's meaning"), 4 ("My life has a clear sense of purpose"), and 5 ("I have a good sense of what makes my life meaningful") for country, but none for gender, age group, or education level. The Search subscale yielded disordered category threshold calibrations, but after collapsing some of the response categories representing low and medium levels of the target construct, a subscale that demonstrated good fit to the Rasch model, good targeting, and no differential item functioning resulted. CONCLUSIONS In terms of this particular scale, adaptation of the rating scale and removal of item 9 is recommended. Country-level parameter estimates may be needed for items that exhibited differential item functioning. The study also has significant implications for the theory, measurement, and practice of meaning in and quality of life in general. Reasons for and the far-reaching implications of the insensitivity of the Presence subscale for high levels of presence of meaning on, for example, the correlation between meaning in life and indicators of health are contemplated. Further investigation of the construct's nature and measurement, especially at high levels, is indicated.