Each study is weighted based on three objective factors — number of subjects, type of study, and time period covered — as follows:
For each study, the sum total is positive if the study supported use of the substance or activity studied. The sum total takes a negative sign if the study did not support use of the substance or activity studied. The sum total is set to 0 if the study was inconclusive (some supporting evidence but too weak to achieve statistical significance, or conflicting evidence).
All studies’ results are summed for the final summary “score” for that substance or activity.
In this way, the preponderance of the evidence will determine the score. Additionally, substances and activities that are more-studied and more rigorously studied will have higher scores.
If a substance or activity has overwhelmingly positive studies but they are all small, short-term, and/or non-human trials, the score may not be high. In that case, there will be a note that further and more rigorous study is warranted to confirm the preliminary findings.
If a particular study is groundbreaking and negates the results of many other past studies, a special note will be made in the summary text.
Lastly, in the initial phase of this project, all studies included must be either publicly available or have enough information in the abstract to make their methods and results clear. If all studies were readily available, I would happily include them, but that is not the case at present.