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Table 2 The use of methods to reduce the risk of selection bias

From: Risk of selection bias in randomised trials

 

Trials (n = 152)

Recruiters blinded? – number (%)

 

 No

1 (1)

 Yes

2 (1)

 Not stated

149 (98)

Used simple or restricted randomisation? – number (%)

 

 Simple randomisation

4 (3)

 Restricted randomisation

95 (63)

 Not stated

53 (35)

Type of restricted randomisation used – number (%)

 

 Permuted block

72/95 (76)

 Minimisation

21/95 (22)

 Other

2/95 (2)

Balanced for prognostic factors after restricted randomisation? – number (%)

 

 No

42/95 (44)

 Yes

53/95 (56)

Randomisation stratified by site of recruitment? – number (%)

 

 No

41 (27)

 Yes

67 (44)

 Not stated

44 (29)