Measurement in Health Psychology Research and Practice

Health psychology is the investigation of psychological and behavioral processes in health, illness and healthcare. It investigates the behavior of people who are healthy or ill as well as practitioners and policymakers delivering or making decisions that influence healthcare. Measures may be used in studies aiming to elucidate and understand processes to advance theory and evidence, or to gain
greater understanding or even intervening to improve health and healthcare outcomes. A wide range of research designs are used including observational, intensive longitudinal (or ecological momentary assessment [EMA]), experimental laboratory, pre-post event or intervention, and randomized controlled trials. Frequently investigations measure a target behavior or psychological state and
examine a) whether it can be predicted or influenced by antecedents (events, environments, cognitions, interventions) and b) whether it predicts or influences consequences, especially health/illness outcomes. Health psychology shares measurement issues that are challenging for psychology in general, including establishing reliability and validity, scaling mental processes, reactivity of measures. Additionally, self-report measures are frequently used to assess symptoms such as pain or reports of health behaviors such as smoking, and these assessments may be used to assess a clinical condition and to guide clinical decisions. They may be validated against an objective measure, but the objective measure may fail to represent the full range, context or occurrence of the target construct and can therefore only give an indication rather than a solid assessment of validity of the self-report. Measures are often used to measure change over time, especially change associated with an intervention or a changing clinical state, and therefore need to be repeatable while retaining
meaning; sensitivity to change may be more important than test-retest reliability. Longitudinal measurement has been aided by the use of digital mobile technologies, including wearables and automatic measurement of physiological processes. Additionally, physiological functioning, especially autonomic, immune and cardiac, are commonly measured. Data collected routinely by healthcare organizations such as attendance at appointments or health outcomes may be useful, but these data may be incomplete or only give indirect evidence of the target behaviors or outcomes. Finally, the context of measurement may determine what is possible: ill patients would be burdened by a long questionnaire; healthcare professionals may have limited time and opportunity to respond to assessments and measures may need to be adapted for a clinical environment. The following sections address measures of key psychological constructs, health-related behaviors and responses to health, illness and healthcare.