Invited commentary: positivity in practice.

Journal Article (Journal Article)

Positivity, or the experimental treatment assignment assumption, requires that there be both exposed and unexposed participants at every combination of the values of the observed confounders in the population under study. Positivity is essential for inference but is often overlooked in practice by epidemiologists. This issue of the Journal includes 2 articles featuring discussions related to positivity. Here the authors define positivity, distinguish between deterministic and random positivity, and discuss the 2 relevant papers in this issue. In addition, the commentators illustrate positivity in simple 2 x 2 tables, as well as detail some ways in which epidemiologists may examine their data for nonpositivity and deal with violations of positivity in practice.

Full Text

Cited Authors

  • Westreich, D; Cole, SR

Published Date

  • March 2010

Published In

Volume / Issue

  • 171 / 6

Start / End Page

  • 674 - 677

PubMed ID

  • 20139125

Pubmed Central ID

  • PMC2877454

Electronic International Standard Serial Number (EISSN)

  • 1476-6256

International Standard Serial Number (ISSN)

  • 0002-9262

Digital Object Identifier (DOI)

  • 10.1093/aje/kwp436


  • eng