Speeding and young drivers. Refer to the British Journal of Educational Psychology (Vol. 8...

Speeding and young drivers. Refer to the British Journal of Educational Psychology (Vol. 80, 2010) study of teenage drivers’ temptation to exceed the speed limit. Recall that in a survey of 258 student drivers taken 5 months after the students had attended a safe-driver presentation, responses (measured on a 7-point scale) to the question “Are you confident that you can resist your friends’ persuasion to drive faster?” had a mean of 4.98 and a standard deviation of 1.62. A MINITAB printout for testing H0: μ = 4.7 againist Ha: μ > 4.7 is shown below.

a.Locate the p -value of the test on the printout. What does the p -value measure?

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b.Give the appropriate conclusion for α = .05 . Does this conclusion agree with your answer to Exercise 6.26d?

Use the applet entitled Hypotheses Test for a Mean to investigate the effect of the underlying distribution on the proportion of Type I errors. For this exercise, take n = 100, mean = 50, standard deviation = 10, null mean = 50, and alternative 6 .

a.Select the normal distribution and run the applet several times without clearing. What happens to the proportion of times the null hypothesis is rejected at the .05 level as the applet is run more and more times?

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b.Clear the applet and then repeat part a , using the rightskewed distribution. Do you get similar results? Explain.

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c.Describe the effect that the underlying distribution has on the probability of making a Type I error.