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Open Access Open Badges Correction

Correction: A simple method for analyzing data from a randomized trial with a missing binary outcome

Stuart G Baker1* and Laurence S Freedman2

Author Affiliations

1 Biometry Research Group, Division of Cancer Prevention, National Cancer Institute, USA

2 Department of Mathematics, Statistics, and Computer Science, Bar Ilan University, Ramat Gan 52900, Israel

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BMC Medical Research Methodology 2004, 4:1  doi:10.1186/1471-2288-4-1

The electronic version of this article is the complete one and can be found online at:

Received:2 January 2004
Accepted:7 January 2004
Published:7 January 2004

© 2004 Baker and Freedman; licensee BioMed Central Ltd. This is an Open Access article: verbatim copying and redistribution of this article are permitted in all media for any purpose, provided this notice is preserved along with the article's original URL.


In this article [1], equation (8) is incorrect because it omitted the covariance terms. Let h denote the number of strata, so s = 1,2,...,h. Let T denote transpose, • denote matrix product, and Diagonal Matrix [vector] denote a matrix of all 0's except for vector on the diagonal. The correct formula is


In our example, the effect of the correction was negligible; the corrected estimated standard error was the same to two significant digits as the incorrect value.

Also for clarification, we note that in the sentence after (11), it is an assumption that, within stratum s, the difference, Δs, does not depend on the unobserved covariate x.


  1. Baker SG, Freedman LS: A simple method for analyzing data from a randomized trial with a missing binary outcome.

    BMC Medical Research Methodology 2003, 3:8. PubMed Abstract | BioMed Central Full Text | PubMed Central Full Text OpenURL

Pre-publication history

The pre-publication history for this paper can be accessed here: