Forced Expiratory Volume

Data 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 Rosners 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