Table 1 The frequency of randomized studies, use of blinding and statistical significance among different income groups in the years1993 and 2003 (numbers in the parentheses represent the 95% CIs of the absolute change)
From: Country development and manuscript selection bias: a review of published studies
| Â | Low | Lower-middle | Upper-middle | High |
|---|---|---|---|---|
Randomized studies: | ||||
1993 | 38/50(76%) | 36/50(72%) | 34/50(68%) | 31/50(62%) |
2003 | 44/50(88%) | 38/50(76%) | 39/50(78%) | 37/50(74%) |
Absolute change (%) | 12 (-2 to 27) | 4(-13 to 21) | 10(-7 to 27) | 12(-6 to 30) |
Blinded studies: | ||||
1993 | 18/50(36%) | 23/50(46%) | 25/50(50%) | 30/50(60%) |
2003 | 23/50(46%) | 16/50(32%) | 22/50(44%) | 23/50(46%) |
Absolute change (%) | 10(-9 to 29) | -14(-32 to 5) | -6(-25 to 14) | -14(-33 to 5) |
Significant results: | ||||
1993 | 29/50(58%) | 30/50(60%) | 38/50(76%) | 34/50(68%) |
2003 | 40/50(80%) | 41/50(82%) | 42/50(84%) | 33/50(66%) |
Absolute change (%) | 22(4 to 39) | 22(5 to 39) | 8(-7 to 24) | -2(-20 to 16) |