The conceptualisation and assessment of child and adolescent well- and ill-being

Grounded in Piagetian epistemology, a key aim of this thesis was to better understand the complex constructs of well- and ill-being. According to Deci and Ryan (2000) the quality of our well-being is fundamental to how much we consider ourselves to be functioning optimally. Yet little is known concerning how children and adolescents conceptualise well- and ill-being. To address this limitation, the overarching aim of this thesis was to develop an assessment tool for use with children and adolescents to meaningfully, validly and reliably measure youngsters’ well- and ill-being via the concepts and words of young people themselves. In Chapter 2, an indicator of well-being (i.e., the subjective vitality scale) often employed with younger populations, was examined in terms of measurement invariance. Findings suggested differences between children and adolescents well-being scores warranted further investigation. In Chapters 3 and 4, a developmental approach was used to explore children’s (7-11 years) and adolescents (12-18 years) understanding and experience of well- and ill-being. A developmental trajectory in well- and ill-being was revealed, which holds implications for valid and reliable assessment in research and practice contexts. Using the young people’s descriptors of well- and ill-being derived an initial questionnaire was presented in Chapter 4. A set of studies presented in Chapter 5 details the development of two multidimensional measures of well- and ill-being (MMWIB-C), one for children and another version for adolescents (MMWIB-A). Evidence of validity and reliability of the new measure(s) outlined in Chapter 5 is promising, suggesting the MMWIB has the potential to validly record and report on the well- and ill-being of children and adolescents in future