Introductory Biostatistics

3.3 (a)0.202;(b)0.217;(c)0.376;(d)0.268.

3.4 Positive predictive value for population A: 0.991, for population B:

0.900.

3.5 (a)Sensitivity¼0.733, specificity¼0.972;(b)0.016;(c)0.301.

3.6 Prevalence Positive Predictive Value

0.2 0.867

0.4 0.946

0.6 0.975

0.7 0.984

0.8 0.991

0.9 0.996

Yes:

prevalence¼

ðPPVÞð 1 
specificityÞ

ðPPVÞð 1 
specificityÞþð 1 
PPVÞðsensitivityÞ

¼ 0 : 133 if PPV¼ 0 : 8

3.7 (a)0.1056;(b)0.7995.

3.8 (a)0.9500;(b)0.0790;(c)0.6992.

3.9 (a)0.9573;(b)0.1056.

3.10 (a)1.645;(b)1.96;(c)0.84.

3.11 102.8¼118.4
(1.28)(12.17).

3.12 20–24 years: 101.23 106.31 141.49 146.57
25–29 years: 104.34 109.00 141.20 145.86
For example, 123.9
(1.645)(13.74)¼101.3.

3.13 (a) 200 þdays: 0.1587; 365þdays:F0;(b)0.0228.

3.14 (a)0.0808;(b)82.4.

3.15 (a)17.2;(b)19.2%;(c)0.0409.

3.16 (a)0.5934;(b)0.0475;(c)0.0475.

3.17 (a)F0(z¼ 3 :79);(b)F0(z¼
3 :10).

3.18 (a)0.2266;(b)0.0045;(c)0.0014.

3.19 (a)0.0985;(b)0.0019.

3.20 Rate¼13.89 per 1000 live births; z¼13.52.

3.21 (a)Left of 2.086: 0.975; left of 2.845: 0.995;(b)right of 1.725: 0.05; right
of 2.528: 0.01;(c)beyondG2.086: 0.05; beyondG2.845: 0.01.

ANSWERS TO SELECTED EXERCISES 509