Stat 301
Lab 3
Due September 22, 2014
Last week's lab looked at data on the heights of children ages 3 to 19 and whether gender
(male or female) could explain variation in height. The data are available on the course
Web site:
http://www.public.iastate.edu/~wrstephe/stat301.html
In this week’s lab assignment we will look at the relationship between a child’s age and
her/his height.
1. Download the data table and use JMP to perform an analysis to model height as a
linear function of age. It is not sufficient to simply hand in JMP output. You must
answer the questions completely. Turn in the JMP output attached at the end of your
written answers.
a) Use Fit Y by X to obtain a plot of Height (Y) versus Age (X). Describe the
general relationship between the two variables.
b) Give the least squares equation of the line that relates Height to Age.
c) Give an interpretation of the estimated slope within the context of the problem.
d) Give an interpretation of the estimated intercept within the context of the
problem.
e) Give the value of R2 and an interpretation of this value within the context of the
problem.
f) Give the value of sY|X, the estimate of the error standard deviation, σ.
g) Test the hypothesis that the slope parameter,  1 , is zero against the alternative that
it is not zero. Be sure to include all the steps for a test of hypothesis.
h) Construct a 95% confidence interval for the slope parameter,  1 . Is this
confidence interval consistent with the results of your test in g)? Explain briefly.
i) Put prediction bands for predicting an individual children’s height from her/his
age on your plot of the data. Do any of the points fall outside the prediction
bands? If so, what are the Age, Gender, Height and predicted Height associated
with each of the points?
j) Use Fit Y by X to construct a plot of Residuals versus Age. Note: You will first
have to Save Residuals. Are there any unusual patterns or points? If so, comment
on the pattern and/or indicate the unusual points.
k) Use Analyze + Distribution to analyze the distribution of residuals. Based on this
analysis, and any plots from the previous analysis, comment on each of the
conditions necessary for regression analysis.
Remember to turn in the JMP output with the answers to the questions.
2. On a separate sheet of paper (this sheet will be graded separately from your answers
to part 1) write a brief summary of what you have learned about the relationship
between the age and height of children between the ages of 3 and 19.
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