Questionnaire validation practice within a theoretical framework: a systematic descriptive literature review of health literacy assessments

OBJECTIVE: Validity refers to the extent to which evidence and theory support the adequacy and appropriateness of inferences based on score interpretations. The health sector is lacking a theoretically-driven framework for the development, testing and use of health assessments. This study used the Standards for Educational and Psychological Testing framework of five sources of validity evidence to assess the types of evidence reported for health literacy assessments, and to identify studies that referred to a theoretical validity testing framework. METHODS: A systematic descriptive literature review investigated methods and results in health literacy assessment development, application and validity testing studies. Electronic searches were conducted in EBSCOhost, Embase, Open Access Theses and Dissertations and ProQuest Dissertations. Data were coded to the Standards’ five sources of validity evidence, and for reference to a validity testing framework. RESULTS: Coding on 46 studies resulted in 195 instances of validity evidence across the five sources. Only nine studies directly or indirectly referenced a validity testing framework. Evidence based on relations to other variables is most frequently reported. CONCLUSIONS: The health and health equity of individuals and populations are increasingly dependent on decisions based on data collected through health assessments. An evidence-based theoretical framework provides structure and coherence to existing evidence and stipulates where further evidence is required to evaluate the extent to which data are valid for an intended purpose. This review demonstrates the use of the Standards’ theoretical validity testing framework to evaluate sources of evidence reported for health literacy assessments. Findings indicate that theoretical validity testing frameworks are rarely used to collate and evaluate evidence in validation practice for health literacy assessments. Use of the Standards’ theoretical validity testing framework would improve evaluation of the evidence for inferences derived from health assessment data on which public health and health equity decisions are based.