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

"BioMed Central will be the most significant development for disseminating the results of biomedical researc h in our lifetime." 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 where 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 , ∆ s , does not depend on the unobserved covariate x. 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. var d var d w var s s h s i () 2 i w w w q q n d d T s s h sz z sz zs s s h) ()/ (1 1 h h s i j h h i h j h i j w N d d d d w w N) / () () / , 2 1 1 1 1 8 ++ = − = − ++ − − − () ∑ ∑ w w w w w d d d d d d var h h h h h = ∂ ∂ = − − − − − (1 2 1 1 2 1 0 ∆ i w DiagonalMatrix w w w N T) ([ ])/. = − ++