Table 2

Changes in research output between 1950 and March 1998, by research methodology

Year of publicationTotalTrend
p value2-150
50–5455–5960–6465–6970–7475–7980–8485–8990–9495–3/98
Meta-analysis000000015390.0418
Observational1036628256572392450.716
Review0000104122626690.0002
Trial123721611221151721026060.0644
Total226132889151193275170929
  • NB: Grand total is 929 not 930 as one study had no publication date.

  • 2-150 χ2 Test for trend from 1950–54 to 1990–94.