Testing of Hypothesis
1. Is there a statistically significant difference between
standard deviations of blood polyphenol level change in the red and white wine
groups in Exercise 17.7?
DATA
Observational studies suggest that moderate use of alcohol
reduces heart attacks, and that red wine may have special benefits. One reason
may be that red wine contains polyphenols, substances that do good things to
cholesterol in the blood and so may reduce the risk of heart attacks. In an
experiment, healthy men were assigned at random to drink half a bottle of
either red or white wine each day for two weeks. The level of polyphenols in
their blood was measured before and after the two week period. Here are the
percent changes in level for the subjects in both groups.
Red Wine 3.5 8.1 7.4 4.0 0.7 4.9 8.4 7.0 5.5
White Wine 3.1 0.5 -3.8 4.1 -0.6 2.7 1.9 -5.9 0.1
2. “The phenomenon of road rage had been frequently
discussed but infrequently examined”. So begins a report based on
interviews with randomly selected drivers. The respondent’s answers to
interview questions produced scores on an “angry/threatening driving
scale” with values between 0 and 19. Here are summaries of the scores:
Group n x bar s
Male 596 1.78 2.79
Female 769 0.97 1.84
a) We suspect that men are more susceptible to road rage
than women. Carry out a test of that hypothesis. (State hypothesis, find the
test statistic and P-value, and state your conclusion.
b) The subjects were selected using random digit dialing.
The large sample sizes make the Normality condition unnecessary. There is one
aspect of the data production that might reduce the validity of the data. What
is it?
ScholarMatic: Explanation & Answer
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