Now, leaving aside the abhorrent nature of the study, let's look at the science here because I think it is VERY REVEALING
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So, they've computed their sample size based on the idea that they want to detect an effect size of 0.25 between two groups But...they didn't include any indication of obese vs lean here. The eventual sample size (150) shows us that
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Instead, it seems almost certain that the original study just looked at lying in fasted vs breakfasted people We can actually see this even more clearly because they ran 36 people through the entire procedure only to exclude them after the fact!pic.twitter.com/YcaJhAfNFh
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This starts to get a bit murky, because I cannot find a pre-registration for the study That's worrying, because changing your hypothesis after running a study is a classic sign of p-hacking
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Another sign is the statistical analysis. I count upwards of 100 comparisons (Fisher's exact test, chi squared etc) with no correction for multiple comparisons That's...worrying
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If you apply a Bonferroni correction to the results, pretty much every statistically significant finding completely disappears, which is not surprising given that they ran SO MANY tests
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Bringing it back home, we have this sentence in the discussion According to supplementary table 4, this simply isn't true!pic.twitter.com/zNm5GfENI8
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Obese people had differences in behaviour, but the statistical comparisons DIDN'T SHOW A SIGNIFICANT DIFFERENCE Pretty major issue, that
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Anyway, the paper is abhorrent regardless, but I think it also shows some worrying signs of being constructed after the fact from a dataset of a trial with different aims
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Oh, another issue - the paper makes an inherently misleading claim about causality. The primary findings were of a subgroup analysis of non-randomized groups (lean vs obese) and so it's not clear whether this was causal anyway
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Because the randomization was simply fasted vs breakfast, the causal attribution for this study should be comparing those two groups, not the subgroups of obese vs lean
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End of conversation
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