Nonetheless, it has barely been given high priority in similar studies thus far conducted [ 7- 10].
Thus, studies with smaller, more specific gene lists are given higher weight than studies with large, less specific lists.
Studies which met five or more of the eight criteria were given higher quality scores.
"In this study the researchers were giving higher doses of vitamin D, and I think we would need larger studies to be confident that there were no negative effects of this higher dose".
Highest priority should be given to studies with clearly defined disease outcomes, quantifiable environmental exposures that may be plausibly related to the disease, and an accessible study population.
Where the studies were equivocal, weighting would be given to those studies with higher methodological validity and statistical power.
Compounds demonstrated or predicted to have highly variable toxic responses may also be given a higher priority for further study, in combination with chemical and other expected modifiers of susceptibility.
For example a gold standard study (in the jargon of medical research, a randomised, controlled trial) would be given an A* rating and high weight and a poor study is graded as "must try harder" and given a low weight.
This is one reason why only two model-based studies were given a high strength of evidence rating.
Higher weight was given to studies that only included participants free of disability at baseline compared to studies that included participants with and without disability at baseline.
