Introductory Biostatistics

12.24 d¼ 0 :196, almost 20%.

12.25 y¼

lnð 0 : 6 Þ

lnð 0 : 7 Þ

¼ 1 : 432

d¼ð 1 : 96 þ 0 : 84 Þ^2

1 þ 1 : 432

1 
 1 : 432

 2

¼249 events

N¼

ð 2 Þð 249 Þ

2 
 0 : 6 
 0 : 7

¼710 subjects or 355 per group

12.26 y¼

lnð 0 : 4 Þ

lnð 0 : 5 Þ

¼ 1 : 322

d¼ð 1 : 96 þ 0 : 84 Þ^2

1 þ 1 : 322

1 
 1 : 322

 2

¼408 events

N¼

ð 2 Þð 408 Þ

2 
 0 : 4 
 0 : 5

¼742 subjects or 371 per group

12.27 y¼

lnð 0 : 4 Þ

lnð 0 : 6 Þ

¼ 1 : 794

d¼ð 1 : 96 þ 0 : 84 Þ^2

1 þ 1 : 794

1 
 1 : 794

 2

¼98 events

N¼

ð 2 Þð 98 Þ

2 
 0 : 4 
 0 : 6

¼98 subjects or 49 per group

12.28 p 1 ¼ 0 :18:(a)N¼590, 245 cases and 245 controls;(b)N¼960, 192
cases and 768 controls;(c)m¼66 discordant pairs andM¼271 case–
control pairs.

528 ANSWERS TO SELECTED EXERCISES