The impact of contamination bias when replicating maltreatment effects on child behavior problems
7 affiliations
- 1National Crime Victims Research and Treatment Center, Medical University of South Carolina, Charleston, South Carolina, United States of America
- 2Center for Healthy Aging, Pennsylvania State University, University Park, Pennsylvania, United States of America
- 3Institute for Quantitative Social Science, Harvard UniversityCambridge, Massachusetts, United States of America
- 4Department of Psychology and Neuroscience, University of North Carolina, Chapel Hill, North Carolina, United States of America
- 5College of Education and Human Development, University of Delaware, Newark, Delaware, United States of America
- 6Department of Communications, Stanford University, Stanford, California, United States of America
- 7Department of Psychology, Stanford University, Stanford, California, United States of America
Abstract
Background: Contamination, when members of a comparison condition receive or are exposed to a treatment under investigation, can bias the direction, statistical significance, and magnitude of treatment effects. Objective: This pre-registered study examined whether contamination biased estimates when replicating child maltreatment effects on two established outcomes, externalizing and internalizing behavior problems. Methods: A multi-wave, U.S. national probability sample of children and families involved with child protective services (N = 4000; Age = 0–17.5; Sex = 48% Female; Race = 60% White; Ethnicity = 30% Hispanic). Child maltreatment and comparison conditions were established using official case records and contamination was identified as caregiver-reported maltreatment for those children assigned to the comparison condition. Outcomes were 6-month frequencies of externalizing and internalizing behaviors, represented in T-scores, three years post-maltreatment exposure. Results: The prevalence of contamination in this study was 96%. Propensity score analyses that ignored contamination revealed that maltreatment exposure had no impact on externalizing behaviors (b = 0.28, p = .746) or internalizing behaviors (b = 0.27, p = .744), failing to replicate prior research. However, propensity score analyses that corrected contamination replicated prior research by generating estimates that were in the expected directions, statistically significant, and moderate to large in effect magnitude for externalizing (b = 8.72, p = .002, SMD = 0.74) and internalizing behavior problems (b = 9.96, p < .001, SMD = 0.90). Conclusion: Correcting contamination has the potential to improve the replication of child maltreatment effects, strengthening the generalizability of results.
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BibTeX
@article{olson2026impact,
title = {{The impact of contamination bias when replicating maltreatment effects on child behavior problems}},
author = {Anneke E. Olson and John M. Felt and Noah Greifer and Zachary F. Fisher and Kenneth A. Shores and Nilam Ram and Chad E. Shenk},
journal = {PLOS One},
year = {2026},
month = oct,
doi = {10.1371/journal.pone.0358837},
url = {https://doi.org/10.1371/journal.pone.0358837},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - The impact of contamination bias when replicating maltreatment effects on child behavior problems
AU - Anneke E. Olson
AU - John M. Felt
AU - Noah Greifer
AU - Zachary F. Fisher
AU - Kenneth A. Shores
AU - Nilam Ram
AU - Chad E. Shenk
PY - 2026
DA - 2026/10/06
JO - PLOS One
DO - 10.1371/journal.pone.0358837
UR - https://doi.org/10.1371/journal.pone.0358837
AB - Background: Contamination, when members of a comparison condition receive or are exposed to a treatment under investigation, can bias the direction, statistical significance, and magnitude of treatment effects. Objective: This pre-registered study examined whether contamination biased estimates when replicating child maltreatment effects on two established outcomes, externalizing and internalizing behavior problems. Methods: A multi-wave, U.S. national probability sample of children and families involved with child protective services (N = 4000; Age = 0–17.5; Sex = 48% Female; Race = 60% White; Ethnicity = 30% Hispanic). Child maltreatment and comparison conditions were established using official case records and contamination was identified as caregiver-reported maltreatment for those children assigned to the comparison condition. Outcomes were 6-month frequencies of externalizing and internalizing behaviors, represented in T-scores, three years post-maltreatment exposure. Results: The prevalence of contamination in this study was 96%. Propensity score analyses that ignored contamination revealed that maltreatment exposure had no impact on externalizing behaviors (b = 0.28, p = .746) or internalizing behaviors (b = 0.27, p = .744), failing to replicate prior research. However, propensity score analyses that corrected contamination replicated prior research by generating estimates that were in the expected directions, statistically significant, and moderate to large in effect magnitude for externalizing (b = 8.72, p = .002, SMD = 0.74) and internalizing behavior problems (b = 9.96, p < .001, SMD = 0.90). Conclusion: Correcting contamination has the potential to improve the replication of child maltreatment effects, strengthening the generalizability of results.
SN - 1932-6203
ER -