Table 3

Calculations for the log-rank test to compare treatments for the data in Table 1
Survival time (days)
 Treatment group
 Number known to be alive (ri)
 Deaths (di)
 Risk for death (di/ri)
 Number known to be alive from treatment group 2 (r2i)
 Expected number of events in treatment group 2 (E2i)
0





1
 2
 15
 2
 2/15 = 0.133
 8
 8 × 0.133 = 1.07
1
 2




4
 2
 13
 1
 1/13 = 0.077
 6
 6 × 0.077 = 0.46
5
 2
 12
 1
 1/12 = 0.083
 5
 5 × 0.083 = 0.42
6+
 2
 11
 0
 0/11 = 0
 4
 4 × 0 = 0.00
8
 1
 10
 1
 1/10 = 0.100
 3
 3 × 0.100 = 0.30
9
 2
 9
 1
 1/9 = 0.111
 3
 3 × 0.111 = 0.33
9+
 2
 8
 0
 0/8 = 0
 2
 2 × 0 = 0.00
12
 1
 7
 1
 1/7 = 0.143
 1
 1 × 0.143 = 0.14
15+
 1
 6
 0
 0/6 = 0
 1
 1 × 0 = 0.00
22
 2
 5
 1
 1/5 = 0.200
 1
 1 × 0.200 = 0.20
25+
 1
 4
 0
 0/4 = 0
 0
 0 × 0 = 0.00
37
 1
 3
 1
 1/3 = 0.333
 0
 0 × 0 = 0.00
55
 1
 2
 1
 1/2 = 0.500
 0
 0 × 0 = 0.00
72+
 1










E2 = 2.92

Bewick et al. Critical Care 2004 8:389   doi:10.1186/cc2955