Peer review
Short definition
Peer review is the process in which a scientific work is assessed by independent experts in the same field before it is published in a scientific journal.
In plain language
Reviewers check whether the methods are appropriate, whether the conclusions follow from the data and whether the work is relevant, and may ask for changes or recommend rejection. It is an important filter, but it does not guarantee that a study is right. Preprints, published before this review, and promotional materials have not been through it, which is worth bearing in mind when weighing claims about health technologies.