Salami-Slicing in Obesity Research
Four new publications in Obesity tackle salami-slicing and other issues of scientific integrity in obesity research with stunning clarity. John Ioannidis provides an overview of the issues in a commentary and calls out the increasingly common practice of salami-slicing data from both observational and randomized trials of nutrition and obesity. Some observational datasets have been mined for hundreds of publications. Even randomized trials are being dredged for so many analyses that credibility stretches thin.
Ioannidis moves on to consider the breadth of issues raised by three publications that follow his commentary:
- Common scientific and statistical errors in obesity research
- Issues with uncontrolled trials of obesity treatment
- Placebo effects in obesity
Ioannidis suggests a framework for addressing these issues that begins with identifying them, moves on to correcting them wherever possible, embracing them and accepting them in some cases, and in other cases, abandoning research when inherent problems with bias and validity cannot be resolved. To illustrate his point, he says:
For example, the continuous production of thousands of papers of observational epidemiology that assess one nutrient at a time in association with one outcome has reached the point of even being ridiculed by hoaxes, as in the recent chocolate and weight loss hoax. When it is known, after thousands of published papers, that effect sizes are expected to be tiny, observational studies will be unable to eliminate noise to a point that offers reasonable certainty about the validity of observed results.
Enough. Salami slices belong on a charcuterie board. Scientific and statistical rigor should leave no room for them in obesity research.
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March 30, 2016