The third variable is referred to as the moderator variable or simply the moderator. Moderating variable are typically an interaction term in statistical models. Consider, for example, a meta-analysis based on 120 studies of whether or not homework worked. The third was based at the University of Adelaide (see Winefield et al. Prior research had suggested a main effect of social support on quality of life. Even so, relying on a purposive sample of sites that are heterogeneous on many attributes except for volunteering is only logically defensible if researchers know from other sources that no confounds are associated with all the hospitals being volunteers for the clinical trial. 'Moderating' implies greater control, direction and responsibility for outcomes. In either case, they affect the magnitude of the relationship between an independent variable and a dependent one. With adequate sample sizes per group, one can probe the robustness of a relationship across the subgroups sampled. Cognition and Perception, Developmental Psychology, General Psychology, Psychology and Film: M... academy awards, oscars, psychology and film, psychology in film, theory of mind. For instance, imagine researchers are evaluating the effects of a … Otherwise, there is nothing unique about university hospitals. It explains how or why there is a relation between two variables. Moderators may be characteristics of people or characteristics of situations. Let’s look at some examples in psychological research. ‘Cross-design synthesis’ is a relatively new research strategy for combining the results from diverse, complementary studies, such as randomized controlled studies and administrative databases, to improve knowledge about interventions and to inform policy decisions. It is not random sampling since individual studies are selected for their relevance to the hypothesis and the hope is to achieve a census of all published and unpublished studies. T.D. Synonyms, Acronyms and Abbreviations In meta-analytic practice, generalization depends on the sample of achieved studies including a wide range of human populations, setting types, historical periods, and operationalizations of the cause and effect. So, how is generalization achieved when the object to be generalized is a causal claim? Copyright © AQR, 2013-20. Given the body of research available and the quality of that research with respect to a particular question, it may be determined that doing a meta-analysis is premature for that field. The Federal legislation authorizing the creation of the agency (P.L. However, it should also be recognized that these lines of research go beyond showing that individual differences, in concern for cultivating public appearances, affect self-presentational behaviors. For instance, imagine that you find a positive association between note-taking and performance on an exam. They concluded that ‘the results from the 16 longitudinal studies suggest that unemployment has reliable (negative) effects on mental health’ and that ‘effect size information…suggests that moving from unemployment to employment not only produces a reliable change to mental health, but a change that is “practically significant.”’. These issues set the agenda for the first generation of research and theorizing on self-monitoring, designed primarily to document the relatively ‘situational’ orientation of high self-monitors and the comparatively ‘dispositional’ orientation of low self-monitors (for a review, see Snyder 1987). After all, survey researchers now describe human populations from biased sample data using basically the same weighting technique. Someone who experiences a lot of stress, but has good social support, will show better outcomes (fewer symptoms of depression, anxiety, fatigue...) than someone with low social support. The moderator introduces the participants to each other and keeps updating the forum on new members. These programs of research have demonstrated that these concerns, and their manifestations in expressive control, permeate the very fabric of individuals' lives, affecting their friendship worlds, their romantic lives, their interactions with the consumer marketplace, and their work worlds. The entire sample allows one to conclude that the effect is found despite the internal heterogeneity achieved. A moderator is a variable that affects the strength of the relation between the predictor and criterion variable. About the AQR Glossary: The person who runs a group discussion or focus group. Anxiety, depression, positive and negative self-esteem, and a variety of measures of affect were studied repeatedly. This association may be explained by number of hours studying, which would be the mediating variable. However, the more relevant target population is all studies that could be conducted on the topic, not all those done on it. Nevertheless, a research synthesis can be extremely useful in identifying obstacles in the literature that need to be addressed and successes that can be built on to guide future studies. 1995). 1991, Graziano and Waschull 1995), cross-cultural studies (e.g., Gudykunst 1985). Moderators may be characteristics of people or characteristics of situations. 1997). This discovery has had important practical implications, and has stimulated the consideration of hypotheses as to why this might be, illustrating the impact of what Cooper has called ‘review-generated evidence.’. A mediating variable explains the relation between the independent (predictor) and the dependent (criterion) variable. It can be qualitative (e.g., sex, race, class…) or quantitative (e.g., drug dosage or level of reward). If you are a qualitative research consultant or a business offering qualitative The moderator "Z" is used to assess the strength between the two variables "X" and "Y" (independent and dependent respectively). Groups of unemployed people almost always have poorer mental health than groups of otherwise similar but employed people and unemployment is overwhelmingly found to be the cause of poor mental health rather than the result of it. Effective coping with unemployment is also widespread. This can prevent the overgeneralization that occurs when researchers conclude that a relationship found with the entire sample holds in each subgroup within the sample. The following vignettes are meant to provide a flavor of some of the more contemporary applications of meta-analysis and the central role that meta-analysis plays in explanation, program evaluation, and in informing policy decisions.