Individual Changes from Intervention: How Much Can We Expect? Tom Baranowski, Ph.D. Professor of Pediatrics (Behavioral Nutrition) USDA/ARS - Children’s Nutrition Research Center Baylor College of Medicine Houston, TX
Save the Best for Last? OR Antagonize the Fewest People Since Most People Have Already Left?
Effect Sizes Objectives: • Review school based interventions • Provide critique of literature
Inclusionary Criteria To enhance confidence in estimates: • School as unit • Adequate power To assess interesting possibilities: • Environment vs. curriculum • Innovation
Elementary Schools: CATCH Eat Well & Keep Moving High 5 Alabama Pathways Bienestar Cafeteria Power Plus Middle Schools: Planet Health MSPAN FV Make the Marks Studies Included
Overview of Effect Sizes • Changes in adiposity and related behaviors have been found • But not always • Sometimes moderated effects • Changes tend to be small in absolute amounts • But one economic analysis suggests even small changes can be cost effective
Overview of Effect Sizes • Desired changes tend to occur in treatment & control groups • Minimizing differences • Not sure want decreases in kcal • But qualitative changes (more likely to get)
Overview of Effect Sizes • Reported in original units, not in SD units • Error will vary across studies • Reflected in SD • Compensation of effects outside of school?
Hard to Compare • Different interventions • Different measures • Different methods • Controlled for different variables • Reported results in different ways • Logically inconsistent across variables within studies • Inconsistent findings across studies
Mediating Variable Model (Conceptual) Intervention Design Moderating Variables Implementation Mediating Variables Outcomes Rewards?
Mediating Variable Model (2) (see Baranowski, et al, 2003 Obesity Research)
Mediating Variable Model (3) A model for program planning and outcome analysis
B A R R I E R S -Type -Diff Content -Types -Levels N1 Exposure Initial Use Continued Use -Preference -Type -Type -Extent -Amount -Amount Design & Development of Intervention Implementation -Fidelity -Extent N2 Exposure Initial Use Continued Use -Preference -Type -Type -Extent -Amount -Amount Resources -Types -Levels Nk Exposure Initial Use Continued Use -Preference -Type -Type -Extent -Amount -Amount Reach -Depth -Spread (Baranowski T, Stables G. Process Evaluation of the 5-A-Day Projects. Health Education &Behavior 2000, 27:157-166.) Process Evaluation as Mediators
Intervention Implementation • What are the 5 major contributors to obesity in each age group? • Provide foci for intervention • How much change is needed to move physiological variables? • Need more controlled research, diet & PA • How much change get when move physical variables?
Intervention Implementation • Need for innovation • Basic research on manipulating moderators • New procedures • Cameras with statements • Low cost / non curricular • Interactive multimedia games
Intervention Implementation • Need innovation (continued) • New theories • Self concept/cognitive dissonance • Theory of planned behavior (EU) • Family influences • Food shopping? • New locations • Summer day camp • Gender & age difference in design - especially PA
Implementation Psychosocial Change • Need to monitor implementation (50%, 22%) • Need to find ways around classroom teachers • New PS measures - IRT?
Psychosocial Change Behavior Change • Need more basic correlates research • Not enough range in normal PS or behavior to detect relationships? • Random (chaos theory) or determinate? • Need mediating variables analyses • Need moderating variable analyses • Gender • SES • Local environment
Behavior Change Psychosocial Change Adiposity Change • Does BMI discourage PA? When? • PROP sensitivity predispose to obesity? • Role of the hormones (leptin, ghrelin) in obesity prevention? • Mediating vs. moderating effects?
Need a National Discussion • Role of schools? • Role of families? • Role of government? • Role of child agencies? • Boy Scouts, YMCA
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