Transportability of Trial Results Using Inverse Odds of Sampling Weights

Daniel Westreich, Jessie K. Edwards, Catherine R. Lesko, Elizabeth Stuart, Stephen R. Cole

Research output: Contribution to journalArticlepeer-review


Increasingly, the statistical and epidemiologic literature is focusing beyond issues of internal validity and turning its attention to questions of external validity. Here, we discuss some of the challenges of transporting a causal effect from a randomized trial to a specific target population. We present an inverse odds weighting approach that can easily operationalize transportability. We derive these weights in closed form and illustrate their use with a simple numerical example. We discuss how the conditions required for the identification of internally valid causal effects are translated to apply to the identification of externally valid causal effects. Estimating effects in target populations is an important goal, especially for policy or clinical decisions. Researchers and policy-makers should therefore consider use of statistical techniques such as inverse odds of sampling weights, which under careful assumptions can transport effect estimates from study samples to target populations.

Original languageEnglish (US)
Pages (from-to)1010-1014
Number of pages5
JournalAmerican journal of epidemiology
Issue number8
StatePublished - Oct 15 2017


  • Causal inference
  • Epidemiologic methods
  • External validity
  • Generalizability
  • Transportability

ASJC Scopus subject areas

  • Epidemiology

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