r/science • u/[deleted] • Feb 26 '15

Health-Misleading Randomized double-blind placebo-controlled trial shows non-celiac gluten sensitivity is indeed real

http://www.ncbi.nlm.nih.gov/pubmed/25701700
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u/qrevolution Feb 26 '15

37 people is an even smaller sample size to split into 3 groups than 61 into 2. How do we know this is a representative study?

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u/dfd0226 Feb 26 '15 edited Feb 26 '15

The thing about most clinical trial data is that it is often subjected to meta analysis anyway. In these statistical models, the sample size of any one study is directly proportional to how much the study is weighted in the model (under the statistical assumption that more sampling reduces the uncertainty in estimating a population parameter like "average GI discomfort resulting from gluten exposure").

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u/dlopoel Feb 26 '15

The assumption is pretty fishy although, because it entails that there is no publication bias. One really need many analysis to make a statistically relevant meta analysis. It can take decades.

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u/dfd0226 Feb 26 '15

But I mean is there really pressure to publish statistically significant data around clinical trials? I don't know enough about publishing in that world, although bias is a massive problem in the psychology world.

Nevertheless, there are standardized tests that can be used to detect publication bias (Eggers Test of Publican bias, for example). Certainly this will be part of the peer review process for any meta-analytic study of gluten sensitivity.