Factorial validity and invariance of the Life Satisfaction Index in older people across groups and time: Addressing the heterogeneity of age, functional ability, and depression Cecilia Fagerstro ¨m a, *, Magnus Lindwall b , Anne Ingeborg Berg b , Mikael Rennemark a a School of Health Science, Blekinge Institute of Technology, SE-371 79 Karlskrona, Sweden b Department of Psychology, University of Gothenburg, Sweden 1. Introduction Life satisfaction may mean different things for different people and may also be dependent on a person’s age. Systematic variation in the meaning of well-being as reflected by age was explored in a study by Bowling (2010), who found older individuals to be more inclined to define life satisfaction as being able to continue to do the things they had always done. This finding illuminates the complexity that research on well-being and life satisfaction needs to address and also demonstrates the importance of identifying relevant targets for health promotion and health care in different age groups with different needs. However, so far, research on life satisfaction has commonly neglected the complexity of the subject by utilizing unidimensional models or by presenting life satisfac- tion in terms of universal outcomes aggregated from a total sum produced by scores of instruments, and by disregarding the subscales (Wallace and Wheeler, 2002). This procedure needs to be called in question given that life satisfaction is a multidimensional concept. Given the great heterogeneity in physical and mental function among older people, investigations able to describe the diversity of life satisfaction are essential. The complexity of capturing the meaning of life satisfaction calls for using carefully developed and valid life satisfaction instruments that show robust measurement qualities also on a factorial level, and which are also adapted to the diversity of the chosen population. The LSIA (Neugarten et al., 1961) is one of the earliest and most widely used (Wallace and Wheeler, 2002) scales measuring life satisfaction in older people. The LSIA was constructed to reflect five underlying dimensions: two about the current life situation (zest and mood tone) and three about the life history and wholeness of life (resolution and fortitude, Congruence between desired and achieved goals and positive self concept). The aim of the scale is to capture life satisfaction in respondents using an internal frame of reference. The LSIA targets the subjective evaluation of a person’s own present and/or past life (Wallace and Wheeler, 2002). Since Neugarten and colleagues developed the scale in the 1960s, a number of studies have generated modified versions of the original LSIA instrument that fit the actual data better and thereby improving the usefulness of the instrument. The majority of previous studies have failed to confirm Neugarten Archives of Gerontology and Geriatrics 55 (2012) 349–356 A R T I C L E I N F O Article history: Received 18 June 2011 Received in revised form 26 September 2011 Accepted 3 October 2011 Available online 4 November 2011 Keywords: Depression Factorial invariance Functional ability Gender Life satisfaction Old age A B S T R A C T In the last decades, extensive research efforts have been directed at exploring life satisfaction in old age, and the Life Satisfaction Index A (LSIA) scale, developed by Neugarten et al. in the 1960s, is one of the most commonly used instruments. However, studies have focused on predicting and comparing changes in people’s life satisfaction without testing if the LSIA instrument is equally valid for different subgroups of people. The present study investigated the underlying dimensions of the LSIA in a Swedish population (n = 1402) of people 60–96 years of age. The study also examined factorial invariance across age, gender, functional ability and depression during a six-year period. The results showed that while a five-factor solution of the LSIA did not exhibit an acceptable fit to the data, a three-factor solution did show a close fit. The two three-factor models that demonstrated the best fit showed invariance across gender and across time, but noninvariance across groups with different levels of reduced functional ability, depressive symptoms and age. These findings suggest that the psychometric properties of life satisfaction instruments like the LSIA need to be taken into consideration before drawing conclusions about life satisfaction when comparing older people of different ages and with different depression and function levels. ß 2011 Elsevier Ireland Ltd. All rights reserved. * Corresponding author. Tel.: +46 0455 385445; fax: +46 0455 385407. E-mail addresses: cecilia.fagerstrom@bth.se, cfa@bth.se (C. Fagerstro ¨ m). Contents lists available at SciVerse ScienceDirect Archives of Gerontology and Geriatrics jo ur n al ho mep ag e: www .elsevier .c om /lo cate/ar c hg er 0167-4943/$ – see front matter ß 2011 Elsevier Ireland Ltd. All rights reserved. doi:10.1016/j.archger.2011.10.007