Forced Expiratory VolumeData Description

One measure of forced expiratory volume (FEV) is the amount of air an individual can exhale in the first second of a forceful breath. Bernard Rosner et al studied the long-term effects of smoking and second-hand smoke.¹ They also measured the FEV of teens. The original data source from Rosner's cross-sectional study² of subjects under age 19 included the variables: age, height, sex, smoking status, and FEV. The dataset was later provided to Michael Kahn for educational purposes.³

For the current inquiry, we are interested in whether teens who smoke have a lower FEV on average than teens who do not smoke. We included subjects aged 13-15 only.

The data may be obtained from the following spreadsheet and copied and pasted into StatCrunch: SIP_Data__FEV.csvDownload SIP_Data__FEV.csv

Statistical Analyses

Treat the data as a random sample and perform a total of four hypothesis tests. One for the overall group of teenage subjects, and one for each age group: 13-year-olds, 14-year-olds, and 15-year-olds. For each test, use the mean FEV of nonsmokers in the associated group as the null hypothesis. Do the data suggest that the mean FEV of smokers is less than the mean FEV of nonsmokers? Perform all tests at a significance level of = 0.05.

Hypothesis Test Considerations

For each hypothesis test include the following:

• State null and alternative hypotheses clearly regarding the well-defined parameter of interest.
• Provide summary statistics such as sample mean and sample standard deviation.
• Satisfy all conditions required to perform the test, supplying a normal probability plot and boxplot where needed.
• Interpret the meaning of the calculated test statistic within its proper context.
• Interpret the meaning of the calculated P-value within its proper context.
• State an accurate decision and conclusion of the test.

Implications of the Study

Address the bulleted ideas below regarding study outcomes. Other variables within the dataset or information from another cited source may be used, though not required.

• Discuss in detail the similarities and the differences among the results of the four hypothesis tests.
• What are the implications of this study in terms of the pulmonary function of teens?
• What are the limits of the conclusions drawn about the pulmonary function of teens?
• Speculate about potential biases of this study, the effects of potentially confounding variables, and/or subsequent research ideas.

Age (yrs)	FEV (liters)	Height (in.)	Gender (0=female, 1=male)	SM (0=nonsmoker, 1=smoker)
13	4.336	69.5	1	0
13	3.816	63.5	0	0
13	3.549	68	1	0
13	3.147	64	0	0
13	4.305	68.5	1	0
13	3.906	67	1	0
13	2.819	62	0	0
13	3.994	67	1	0
13	3.193	70	1	0
13	3.745	68	0	0
13	3.887	67.5	1	0
13	2.646	61.5	0	0
13	2.976	65.5	1	0
13	3.06	61.5	0	0
13	2.704	61	0	0
13	2.434	65.4	0	0
13	4.225	74	1	0
13	3.089	67.5	1	0
13	4.877	73	1	0
13	4.448	69	1	0
13	3.984	71	1	0
13	3.255	66.5	0	0
13	3.331	65.5	0	0
13	5.083	74	1	0
13	3.056	63	0	0
13	2.449	63	0	0
13	4.232	70.5	1	0
13	2.531	61	1	0
13	3.577	63.5	0	0
13	3.141	61	0	0
13	3.208	61	0	1
13	4.789	69	1	1
13	2.599	62.5	0	1
13	4.756	68	1	1
13	3.086	67.5	0	1
13	2.216	68	0	1
13	3.078	66	0	1
13	3.297	65	0	1
13	2.677	67	0	1
13	3.297	65	0	1
13	3.785	63	0	1
13	3.152	62	0	1
13	4.045	69	1	1
14	3.381	63	1	0
14	3.741	68.5	1	0
14	4.842	72	1	0
14	3.436	62.5	1	0
14	4.683	68.5	1	0
14	4.273	72.5	1	0
14	3.395	67	0	0
14	3.169	64	0	0
14	4.111	71	1	0
14	2.538	71	0	0
14	3.68	67	1	0
14	3.585	70	1	0
14	2.891	62	0	0
14	3.78	70	1	0
14	4.271	72.5	1	0
14	2.934	64	0	0
14	2.997	64.5	0	0
14	3.806	68	1	0
14	2.236	66	0	1
14	3.428	64	0	1
14	3.957	72	1	1
14	3.074	65	0	1
14	4.309	69	1	1
14	2.276	66	1	1
14	4.763	68	1	1
15	4.284	70	1	0
15	4.279	67.5	1	0
15	4.5	70	1	0
15	2.635	64	0	0
15	5.793	69	1	0
15	3.985	71	1	0
15	3.731	67	1	0
15	2.887	63	0	0
15	3.211	66.5	0	0
15	4.506	71	1	1
15	2.679	66	0	1
15	2.198	62	0	1
15	3.004	64	0	1
15	3.122	64	0	1
15	3.33	68.5	0	1
15	3.799	66.5	1	1
15	2.264	63	0	1
15	2.278	60	0	1
15	3.727	68	1	1