from an email from Jakob Nielsen
Quantitative Research is Often Wrong
The Economist has a nice analysis of the high probability of wrong quantitative results being published in academic journals. In one example, cancer researchers tried to replicate 53 published studies but could only confirm the findings from 6. In another example, pharmaceutical researchers only got the same result a quarter of the time when repeating 67 so-called “seminal” studies.
The article has a helpful visualization of the statistical outcome of 1,000 research studies under fairly reasonable assumptions: 125 of the studies would be published, containing 80 correct results and 45 wrong results. The remaining 875 studies would have a much higher accuracy rate of 97%, but because they didn’t find anything interesting they would not be published. Because of this publication bias, only 64% of published results would be true, in this example, despite following research protocols that produced good accuracy among all (published, as well as non-published) studies.
There is a longer article at the website: http://www.nngroup.com/articles/risks-of-quantitative-studies/