title: Regression to the Mean: A Commonly Overlooked and Misunderstood Factor Leading to Unjustified Conclusions in Pediatric Obesity Research.
abstract: OBJECTIVE
  In this paper we discuss what regression to the mean (RTM) is, the magnitude of RTM in realistic situations, interpretation of RTM, and recommendations for how to address RTM in study design.
  
  
  METHODS
  Public health research faces many challenges in conducting gold standard randomized, controlled trials (RCT). Although there are many threats to validity in uncontrolled trials, RTM is often overlooked or not adequately considered. RTM is a statistical phenomenon that occurs with any pair of variables that have a correlation not equal to |1.0|. With RTM, subjects' average values on an outcome variable (e.g., BMI) change in a systematic direction over time despite there being no treatment effect. Without a proper control group, changes thought to be associated with an intervention may be due entirely to RTM. Investigators may draw erroneous conclusions based on results showing greater declines in a variable among participants with higher baseline of that variable compared to those with lower baseline of that variable, and label this evidence for differential treatment efficacy.
  
  
  CONCLUSIONS
  Ignoring RTM can lead to unsubstantiated conclusions about the effects of treatments. These conclusions can lead to the waste of time, money, and other resources, which distract from finding appropriate interventions. When a true RCT design is not feasible, reasonable design alternatives involving nonrandomized control groups should be implemented.
authors.affiliation: 1 Department of Pediatrics, Division of General Pediatrics and Adolescent Medicine, The University of North Carolina at Chapel Hill , Chapel Hill, NC.|2 Department of Health Policy and Management, The University of North Carolina at Chapel Hill , Chapel Hill, NC.
authors.forename: Asheley
authors.initials: A
authors.lastname: Cockrell Skinner
authors.affiliation: 3 Nutrition Obesity Research Center, University of Alabama at Birmingham , Birmingham, AL.|4 Office of Energetics, University of Alabama at Birmingham , Birmingham, AL.
authors.forename: TaShauna U
authors.initials: TU
authors.lastname: Goldsby
authors.affiliation: 3 Nutrition Obesity Research Center, University of Alabama at Birmingham , Birmingham, AL.|4 Office of Energetics, University of Alabama at Birmingham , Birmingham, AL.|5 Department of Biostatistics, University of Alabama at Birmingham , Birmingham, AL.
authors.forename: David B
authors.initials: DB
authors.lastname: Allison
mesh_terms: D003627:Data Interpretation, Statistical; D006302:Health Services Research; D006801:Humans; D015233:Models, Statistical; D063766:Pediatric Obesity; D000072440:Public Health Systems Research; D016032:Randomized Controlled Trials as Topic; D012044:Regression Analysis; D012107:Research Design