An Introduction to Sensitivity Analysis for Unobserved Confounding in Nonexperimental Prevention Research
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Despite the fact that randomization is the gold standard for estimating causal relationships, many questions in prevention science are often left to be answered through nonexperimental studies because randomization is either infeasible or unethical. While methods such as propensity score matching can adjust for observed confounding, unobserved confounding is the Achilles heel of most nonexperimental studies. This paper describes and illustrates seven sensitivity analysis techniques that assess the sensitivity of study results to an unobserved confounder. These methods were categorized into two groups to reflect differences in their conceptualization of sensitivity analysis, as well as their targets of interest. As a motivating example, we examine the sensitivity of the association between maternal suicide and offspring’s risk for suicide attempt hospitalization. While inferences differed slightly depending on the type of sensitivity analysis conducted, overall, the association between maternal suicide and offspring’s hospitalization for suicide attempt was found to be relatively robust to an unobserved confounder. The ease of implementation and the insight these analyses provide underscores sensitivity analysis techniques as an important tool for nonexperimental studies. The implementation of sensitivity analysis can help increase confidence in results from nonexperimental studies and better inform prevention researchers and policy makers regarding potential intervention targets.
KeywordsSensitivity analysis Causal inference Unobserved confounding Suicide prevention
The authors wish to acknowledge the NARSAD Young Investigator Award to Dr. Holly C. Wilcox, and Dr. Holly C. Wilcox for allowing us to use the motivating example. We also thank the National Institute of Drug Abuse for the training support for S. Janet Kuramoto (1F31DA0263182), the National Institute of Mental Health (NIMH) Prevention Research T32 Training Grant for the training support for Weiwei Liu (T32 MH18834), and NIMH for the support of Elizabeth Stuart’s time (K25 MH083846). This work was performed while Weiwei Liu was a postdoctoral fellow and S. Janet Kuramoto was a student at Johns Hopkins Bloomberg School of Public Health.
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