Introductory Biostatistics

no e¤ect on the blood level of immunoreactive insulin; that is,

H 0 :mbefore¼mafter

State your alternative hypothesis and choice of test size, and draw the

appropriate conclusion.

TABLE E7.2

Blood Levels of

Immunoreactive Insulin

(mU/mL)

Dog Before After

1 350 480

2 200 130

3 240 250

4 290 310

5 90 280

6 370 1450

7 240 280

7.3 In a study of saliva cotinine, seven subjects, all of whom had abstained
from smoking for a week, were asked to smoke a single cigareete. The
cotinine levels at 12 and 24 hours after smoking are given in Table E7.3.
Test to compare the mean cotinine levels at 12 and 24 hours after
smoking. State clearly your null and alternative hypotheses and choice of
test size.

TABLE E7.3

Cotinine Levels (mmol/L)

Subject After 12 Hours After 24 Hours

17324

25827

36749

49359

533 0

61811

7 147 43

7.4 Dentists often make many people nervous. To see if such nervousness
elevates blood pressure, the systolic blood pressures of 60 subjects were
measured in a dental setting, then again in a medical setting. Data for 60
matched pairs (dental–medical) are summarized as follows:

EXERCISES 271