Related Experiment Video
Updated: Apr 20, 2026

Combining Behavioral Endocrinology and Experimental Economics: Testosterone and Social Decision Making
Published on: March 2, 2011
Neighborhood effects in a behavioral randomized controlled trial
Sandi L Pruitt1, Tammy Leonard2, James Murdoch3
1Department of Clinical Sciences, University of Texas Southwestern Medical Center, Dallas, TX, USA; Harold C. Simmons Comprehensive Cancer Center, 5323 Harry Hines Blvd, Dallas, TX 75390-9169, USA.
Abstract:
Randomized controlled trials (RCTs) of interventions intended to modify health behaviors may be influenced by neighborhood effects which can impede unbiased estimation of intervention effects. Examining a RCT designed to increase colorectal cancer (CRC) screening (N=5628), we found statistically significant neighborhood effects: average CRC test use among neighboring study participants was significantly and positively associated with individual patient's CRC test use. This potentially important spatially-varying covariate has not previously been considered in a RCT. Our results suggest that future RCTs of health behavior interventions should assess potential social interactions between participants, which may cause intervention arm contamination and may bias effect size estimation.
Related Concept Videos
Randomized Experiments
Simple randomization
Simple...
Naturalistic Observations
Bystander Effect
Regression Toward the Mean
Group Design
Blinding

