Many providers of alternative therapy say it is inherently unsuited to double-blind randomised trials.
And randomised trials in social work were begun in the 1930s and 1940s.
When teaching small children to read, for example, tightly scripted lessons, their exact content and timing honed by randomised trials, do best.
In fact, randomised trials and systematic reviews of evidence were introduced into the social sciences long before they became common in medicine.
They found that observational studies showed a 38% reduced risk of colorectal cancer, matching well to the 42% reduction shown by randomised trials.
FORBES: Meta-Analysis Adds New Evidence For Cancer Benefits Of Daily Aspirin
Randomised trials have been used to evaluate the effectiveness of driver-education programmes, job-training schemes, classroom size, psychological counselling for post-traumatic-stress disorder and increased investment in public housing.
In the first paper (The Lancet), the authors studied individual patient data from 51 randomised trials of daily aspirin versus no aspirin to prevent vascular events such as heart attacks.
FORBES: Meta-Analysis Adds New Evidence For Cancer Benefits Of Daily Aspirin
An examination of 308 studies from the criminal-justice literature, by David Weisburd of the University of Maryland and his colleagues, found that randomised trials were significantly less likely to report positive outcomes than non-randomised studies.
The authors did this comparison because while randomised trials of aspirin could clearly establish the risk of colorectal cancer, several other solid cancers, and of metastasis, these trials lacked the statistical power to establish effects on less common cancers and on cancers in women.
FORBES: Meta-Analysis Adds New Evidence For Cancer Benefits Of Daily Aspirin
"For the four others investigated, there are no published randomised clinical trials to support their efficacy in weight loss, " Dr Cable added.
Results of methodologically rigorous studies are consistent with those obtained from randomised controlled trials, but sensitivity is particularly dependent on appropriately detailed recording and analysis of aspirin use.
FORBES: Meta-Analysis Adds New Evidence For Cancer Benefits Of Daily Aspirin
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