Classroom Activities: Mediation
Let's practice some examples of mediation. For each research question, identify the independent variable, mediator, and dependent variable. Then choose which Health Behavior Theory is being used for the intervention:
- Is the relationship between program participation and smoking behavior change mediated by self-efficacy?
- Does your program work by first affecting perceived susceptibility which in turn affects behavior change?
- Does your HIV prevention program successfully impact condom use by first impacting the environment?
Answer Key: 1) DV: smoking behavior; M: self-efficacy; IV: program participation; Theory: TRA/TPB 2) DV: behavior change; M: social norms; IV: program participation; Theory: Health Belief Model 3) DV: condom use; M: environmental change; IV: program participation; Theory: Social Cognitive Theory
Have your students work in groups/teams for this exercise. Have each group select a health behavior such as increased physical activity and identify an appropriate psychosocial theory such as the Theory of Planned Behavior that could be used to modify the health behavior. Have the students complete the following:
- Briefly outline an intervention based on the given theory and health behavior.
- Be sure that they operationalize all the theory constructs.
- Identify the possible mediation pathways.
- Specify (write out in algebra) the regression models that may be analyzed to test these mediation pathways.
Be sure that the students are familiar with either MacKinnon or Barron & Kenny's tests for mediation
- Apply the RE-AIM framework to the evaluation of either a) recently passed piece of public health legislation such "no-trans fat" in NYC restaurants or b) a public health intervention.
- After reading about the policy or intervention, have your students diagram the logic model depicting the program's/policy activities and the connection to behavior change.
- Finally, have the students identify the RE-AIM constructs and how they could be or were measured (if there is existing literature).
Publications on Mediators and Moderators:
Baron, R, Kenny D. (1986). The moderator-mediator variable distinction in social psychological research: conceptual, strategic, and statistical considerations. J Pers Soc Psychology, 51:1173-82
Baranowski, T, Anderson, and Carmack, C. (1998). Mediating variable framework in physical activity interventions: how are we doing? How might we do better? American Journal of Preventive Medicine, 15:266-297
MacKinnon, DP, Taborga, MA, Morgan-Lopez, AA. (2002). Mediation designs for tobacco prevention research. Drug and Alcohol Dependence, 68: S69-S83
Cerin, E, Taylor, LM et al. (2006). Small-scale randomized controlled trials need more powerful methods of mediational analysis than the Barron-Kenny method. Journal of Clinical Epidemiology, 59: 457-464
Kraemer, HC, Wilson, GT et al. (2002). Mediators and moderators of treatment effects in randomized clinical trials. Archives of General Psychiatry, 59: 877-883.
Krull, JL, MacKinnon, DP (1999). Multilevel mediation modeling in group-based intervention studies. Evaluation Review, 23(4):418-444.
MacKinnon, DP, Lockwood, CM et al. (2002). A comparison of methods to test the significance of the mediated effect. Psychological Methods, 7(1):83-104.
Further Examples of the RE-AIM Framework in Action:
Glasgow, RE, Kleges, LM et al. (2006). Evaluating the impact of halth promotion programs: using the RE-AIM framework to form summary measures for decision making involving complex issues. Health Education Research, 21(5): 688-694.
Glasgow, RE, Nelson, C et al. (2006). Using RE-AIM metrics to evaluate diabetes self-management support interventions. American Journal of Preventive Medicine, 30(1):67-73.
Bopp, M, Wilcox, S et al. (2007). Using the RE-AIM framework to evaluate a physical activity intervention in churches. Prevention of Chronic Disease, 4(4): A87.
Glasgow, RE, Vogt, TM & Boles, SM. (1999). Evaluating the public health impact of health promotion interventions: the RE-AIM framework. American Journal of Public Health, 89(9):1322-7
Dzewaltowski, DA, Glasgow, RE et al. (2004). RE-AIM: evidence-based standards and a web resource to improve translation of research into practice. Annals of Behavioral Medicine, 28(2): 75-80.