Spatiotemporal meta-analysis: reviewing health psychology phenomena over space and time

Individual studies of health psychology are samples taken in particular places at particular times. The results of such studies manifest multiple processes, including those associated with individual, sample, intervention, and study design characteristics. Although extant meta-analyses of health phenomena have routinely considered these factors to explain heterogeneity, they have tended to neglect the environments where studies are conducted, which is ironic, as health phenomena cluster in space and times (e.g., epidemics). The settings in which study participants live, work, and recreate can be characterised by such environmental factors such as disease, weather, local and broad economic trends, the level of stigmatisation of minority groups, and allostatic load due to all causes. We introduce spatiotemporal meta-analysis, designed to address heterogeneity in study environments. We list potential challenges in developing spatiotemporal meta-analyses, and discuss future directions for this form of systematic reviewing methodology. Logically, to the extent that relevant spatiotemporal information on environmental conditions is available and varies widely, it can help to explain variability in study results that is not explained by individual, sample, study, or intervention features.