The double jeopardy of clustered measurement and cluster randomisation.

Kramer, Michael S; Martin, Richard M; Sterne, Jonathan A C; Shapiro, Stanley; Dahhou, Mourad; Platt, Robert W · BMJ · 2009

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Abstract

<b>Michael S Kramer and colleagues</b> suggest that double clustering might explain the negative results of some cluster randomised trials and describe some strategies for avoiding the problem

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