Invited Commentary: Selection Bias Without Colliders
Abstract In causal analyses, conditioning on a collider generally results in selection bias. Conditioning on a prognostic factor that is independent of the exposure—and therefore is not a collider—can also result in selection bias when 1) the exposure has a non-null effect on the outcome and 2) the...
| Published in: | American Journal of Epidemiology |
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| Format: | Article in Journal/Newspaper |
| Language: | English |
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Oxford University Press (OUP)
2017
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| Online Access: | http://dx.doi.org/10.1093/aje/kwx077 http://academic.oup.com/aje/article-pdf/185/11/1048/29016569/kwx077.pdf |
| Summary: | Abstract In causal analyses, conditioning on a collider generally results in selection bias. Conditioning on a prognostic factor that is independent of the exposure—and therefore is not a collider—can also result in selection bias when 1) the exposure has a non-null effect on the outcome and 2) the association between the noncollider and the outcome is heterogenous across levels of the exposure. This result was empirically demonstrated by Greenland in 1977 (Am J Epidemiol. 1977;106(3):184–187). |
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