Question

3. Some researchers have observed a greater airway resistance in smokers than in non-smokers.
Suppose a study, conducted to compare the percent of tracheobronchial retention of particles in
smoking-discordant monozygotic (identical) twins, yielded the following results:
	Smoking Twin	Non-Smoking Twin
	60.6	47.5
	12.0	13.3
	56.0	33.0
	75.2	55.2
	12.5	21.9
	29.7	27.9
	57.2	54.3
	62.7	13.9
	28.7	8.9
	66.0	46.1
	25.2	29.8
	40.1	36.2

Do these data support the hypothesis that tracheobronchial clearance is slower in smokers? Make no

assumptions and show all work.

Ho:

Ha:

test-statistic:

df:

Exact P value for the test-statistic

Conclusion relative to the hypothesis:

Answer 1

Testing the equality of variances of Smoking and Non-smoking twin,

Using Minitab software, (Stat -> Basic Statistics -> 2 Variances test), we get the following output -

Since P-value > 0.05, so at 5% level of significance, we can conclude that two variances are not significantly different.

To test whether tracheobronchial clearance is slower in smokers, we need to perform 2 sample t test with pooled variance.

Conclusion - There is insufficient evidence to conclude that tracheobronchial clearance is slower in smokers.