Monthly Archives: October 2016

Causes of poor reproducibility in biomedical research

In a previous post, I highlighted a symposium that was held to improve the reproducibility of biomedical research. The published report includes a description of the causes and factors associated with poor reproducibility; these are summarized below. Key causes and factors linked to poor reproducibility False discovery rate and small sample sizes. The false discovery rate is the expected proportion

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Adjusting for differences at baseline in controlled trials

In randomised trials or repeated-measures experimental studies of randomised conditions, researchers often measure a continuous variable at baseline and at the end of the study at follow up. Examples of some outcomes include blood pressure, pain, physiological responses, range of motion, etc. In a BMJ statistics note, methodologists Andrew Vickers and Doug Altman explain how these outcomes can be analysed.

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Poor statistical practices in a leading neuroscience journal

Earlier this year, I was asked to review a manuscript for the Journal of Neurophysiology. I was struck by the use of the standard error of the mean (SEM) to summarize data variability, the selective reporting of exact (e.g., p=0.067) and non-exact (p<0.05) p-values and the interpretation of non-significant results (e.g., p=0.067) as statistically significant. Because the Journal of Neurophysiology

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How to calculate the confidence interval from a p value

Confidence intervals are widely reported in published research and are usually thought to provide more information than p values from significance tests because confidence intervals indicate how precise an estimate is. Sometimes, however, investigators report an estimate (eg. a mean) and p value, but not the confidence interval about the estimate. In a BMJ statistics note, statisticians Doug Altman and

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How false findings become canonized as scientific fact when publication bias is unknown

Scientific inquiry is the process by which new information is generated through experimental, theoretical or observational methods in order to understand the world. As inquiry progresses, some claims eventually achieve enough acceptance by the scientific community and become regarded as “fact”. The more established a fact is, the less likely it is subjected to further verification. However, poor reproducibility of

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