Ignoring regression to the mean leads to unsupported conclusion about obesity.

Asheley Cockrell Skinner,Myles S Faith,Steven B Heymsfield,David B Allison,Angelo Pietrobelli

doi:10.1186/s12966-015-0212-6

Abstract

Childhood obesity remains a substantial health concern for our population and thoughtful attempts to develop and evaluate the utility of programs to reduce childhood obesity levels are needed. Unfortunately, we believe the conclusion by Burke et al. that the HealthMPowers program produces positive change in body composition is incorrect because the results obtained are likely due to regression to the mean (RTM), a well-known threat to the validity of studies that is often overlooked. Using empirical data, we demonstrate that RTM is likely to be the cause for the changes reported. A more reasonable conclusion than the one of effectiveness the authors offered would be that the results did not support the effectiveness of the intervention. Public health officials, parents, school leaders, community leaders, and regulators need and deserve valid evidence free from spin on which they can base decisions.

Highlights

Childhood obesity remains a substantial health concern for our population and thoughtful attempts to develop and evaluate the utility of programs to reduce childhood obesity levels are needed
We read with interest the paper by Burke et al [2] which implemented “A holistic school-based intervention for improving... body composition... in elementary school students” and concluded “The present report demonstrates the effectiveness of the HealthMPowers program in producing positive change in... student body composition...”
* Correspondence: asheley@unc.edu 1The University of North Carolina at Chapel Hill, Chapel Hill, USA Full list of author information is available at the end of the article can meaningfully support: (1) “history,” or historical events that occur at the same time as an intervention which might in actuality have influenced the presumed intervention effect; and (2) “regression to the mean” (RTM), a statistical phenomenon in which scores on average show improvements upward or downward towards the mean over time

Summary

Introduction

Childhood obesity remains a substantial health concern for our population and thoughtful attempts to develop and evaluate the utility of programs to reduce childhood obesity levels are needed. * Correspondence: asheley@unc.edu 1The University of North Carolina at Chapel Hill, Chapel Hill, USA Full list of author information is available at the end of the article can meaningfully support: (1) “history,” or historical events (either global or local) that occur at the same time as an intervention which might in actuality have influenced the presumed intervention effect; and (2) “regression to the mean” (RTM), a statistical phenomenon in which scores on average show improvements upward or downward towards the mean over time.

Results

Conclusion