Skip to main content

Table 1 Distribution of Cochrane reviews over inclusion criteria

From: Are more observational studies being included in Cochrane Reviews?

Study design inclusion criteria

Total

of which published:

pre-2008

2008-2009

Number (per cent)

Number (per cent)

Number (per cent)

(A1) Randomised controlled trials

3,398 (87.2)

2,563 (87.9)

835 (85.2)

(A2) Randomised controlled trials and quasi-randomised trials

277 (7.1)

199 (6.8)

78 (8.0)

(B) Randomised controlled trials, quasi-randomised trials, and (some subset of) observational studies

222 (5.7)

155 (5.3)

67 (6.8)

Total

3,897 (100.0)

2,917 (100.0)

980 (100.0)

  1. Source: Cochrane Database of Systematic Reviews, Issue 3, 2009. A list of the categories assigned to individual reviews is found in the Additional file 1.