Systematic literature reviews are a major form of secondary research, that is, research which uses existing research output as its basis rather that d . They are widely used in medicine and increasingly used in other areas including computer science (esp. software engineering). Systematic reviews are critical to understanding the current state of evidence with respect to critical research question (for example, are existing anti-stroke therapies effective or does test-driven development improve software quality).

Systematic reviews, even of comparatively simple sorts, are extremely labour intensive and require both significant domain knowledge and skills as well as review specific skills (such as information retrieval). For more sophisticated reviews, such as meta-analysis (wherein data from distinct studies is pooled to produce stronger conclusions), both statistical and domain expertise of very particular sorts are required.