CONFIRMATION BIAS IN SEVENTH-DAY ADVENTIST VEGETARIAN RESEARCHERS Currently taking a break from my uni studies to work on my next book, and thought Id share this neat little example of confirmation bias. The study was brought to us by the pro-vegetarian Seventh-day Adventist folks at Loma Linda University, and purported to examine the link between hypothyroidism and vegetarianism vs omnivorism: ncbi.nlm.nih.gov/pmc/articles/PMC3847753/ The method of ascertaining whether subjects had hypothyroidism was, not a medical examination of relevant thyroid biomarkers, but simply a questionnaire which included a question asking whether theyd ever been diagnosed with hypothyroidism by a doctor. The first point is that hypothyroidism is a superb example of a disorder hugely prone to misdiagnosis/underdiagnosis, and simply asking people in a survey whether they have ever been diagnosed with hypothyrodism by a doctor is a truly appalling method of determining the actual incidence of past or present hypothyroidism among subjects in a cohort study. The second point is that the actual study findings, atrocious ascertainment method of hypothyroidism notwithstanding, found NO significant difference in hypothyrodism between vegans and omnivores, and a statistically significant increase in prevalent hypothyroidism among lacto-ovo vegetarians. Yet the authors conclude: With the exception of the lacto-ovo vegetarian diet findings in the prevalence study, vegetarian diets were not associated with increased risk of hypothyroidism. Never mind that lacto-ovo vegetarian diets are the most common form of vegetarian diet... Vegan diets which may be expected to lack iodine due to complete exclusion of animal products tended to be protective. In the conclusion of the abstract, they also write: In conclusion, a vegan diet tended to be associated with lower, not higher, risk of hypothyroid disease. In other words, the statistically significant association between vegetarian diets and hypothyroidism is ultimately brushed off, while the non-significantly lower RR for vegan diets and hypothyroidism is recast as a tendancy towards lower hypothyroidism. Conclusion: Yet more reality-evading bollocks from a group of researchers hopelessly committed to the vegetarian paradigm.
Posted on: Tue, 01 Apr 2014 00:54:00 +0000
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