Stat 401B
Lab 1
Due September 5, 2006
1
Use JMP to analyze the data in problem 1 below. It is not sufficient to simply
hand in JMP output. You must answer the questions completely. Hand in the
JMP output attached at the end of your written solutions.
1. Youths in the East Boston area participated in a study of lung function. The measured
outcome of interest is forced expiratory volume (FEV) in liters, which is, essentially,
the amount of air an individual can exhale in the first second of a forceful breath. The
data set, that is available on the course Web site, contains information on a random
sample of 100 youths in the East Boston area. Go to the course Web site
www.public.iastate.edu/∼wrstephe/stat401.html
to get the JMP or TXT file of the data. Follow the instructions to get the data into
JMP.
(a) Summarize the Fev data graphically by creating a histogram, box plot and normal
probability plot. Referring to these graphs, describe the distribution of Fev. Refer
to each graph separately and comment on the shape of the distribution, if there
are any possible outliers and describe what in the graph supports your statements.
(b) Summarize the data numerically and report a five number summary, the sample
mean and sample standard deviation.
(c) What does the comparison of the mean to the median tell you about the shape
of the distribution of values?
(d) Report the 95% confidence interval for the population mean Fev. Give an interpretation of this interval and the confidence level.
(e) Test the hypothesis that the population mean Fev is 2.5 liters against an alternative that the population mean Fev is greater than 2.5 liters.
The column Sex is coded so that 1=male and 0=female. Make sure the Sex
column has a Data type that is Character and a Modeling type that is
Nominal.
(f) Summarize the Fev values graphically and numerically for each sex. How do males
compare to females?
(g) Do the males differ significantly from the females in terms of average Fev? Perform
the appropriate test of hypothesis. Use α=0.05.
(h) Report the value of a 98% confidence interval for the difference between the mean
Fev for males and females. Give an interpretation of this interval use the interval
to test to see if the difference in mean Fev values between males and females is
statistically significant.
2. On a separate piece of paper write a brief summary of what you have learned about
forced expiratory volume from the analysis of these data.