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Table 1 Age distribution in trial groups: (a) using the sealed envelope method and (b) using central telephone randomization

From: Subversion of allocation concealment in a randomised controlled trial: a historical case study

  (a) Sealed envelope method (b) Central telephone randomisation
  Experimental Control   Experimental Control  
Clinician(s) n median (IQR) n median (IQR) p n median (IQR) n median (IQR) p
All 169 59 (40, 69) 158 63 (33, 63) <0.01 162 59 (48, 69) 165 57 (44, 67) 0.37
1 64 62 (44, 70) 66 61 (44, 72) 0.84 38 57 (42, 66) 37 57 (50, 67) 0.62
2 19 43 (35, 65) 17 52 (43, 65) 0.60 13 60 (48, 71) 12 51 (45, 59) 0.24
3 24 57 (41, 67) 19 72 (53, 76) <0.01 2 61 (-) 2 70 (-) (-)
4 13 33 (25, 41) 13 69 (51, 74) <0.001 14 63 (50, 70) 14 65 (41, 76) 0.99
5 14 47 (37, 65) 14 72 (53, 77) 0.03 12 57 (49, 71) 12 62 (34, 69) 0.91
Others 35 64 (45, 70) 29 59 (47, 71) 0.99 83 59 (48, 69) 88 56 (42, 67) 0.27