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# ANOVA & Students t Test for traffic and stress data

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29. Samples were selected from three populations. The data obtained follow.

Sample 1 Sample 2 Sample 3
93 77 88
98 87 75
107 84 73
102 95 84
85 75
82

100 85 79
_
Xj 100 85 79

2
s 35.33 35.60 43.50
j
2
a. Compute the between-treatments estimate of .
2
b. Compute the within-treatments estimate of

c. At the a = .05 level of significance, can we reject the null hypothesis that the three population means are equal? Explain.

d. Set up the ANOVA table fro this problem

33. Please see attachment file Traffic.

The Texas Transportation Institute at Texas A&M University conducted a survey to determine the number of hours per year drivers waste sitting in traffic. Of 75 urban areas studied, the most jammed urban area was Los Angeles where drivers wasted an average of 90 hours per year. Other jammed urban areas included Denver, Miami, and San Francisco. Assume sample data for six drivers in each of these cities show the following number of hours waster per year sitting in traffic.

a. Compute the sample mean hours wasted per year for each of these urban areas.
b. Using a + .05, test for significant differences among the population mean wasted time for these three urban areas. What is the p-value? What is your conclusion?

A study reported in the Journal of Small Business Management concluded that self employed individuals experience higher job stress than individuals who are not self-employed. In this study job stress was assessed with a 15-item scale designed to measure various aspects
of ambiguity and role conflict. Ratings for each of the 15 items were made using a scale with 1-5 response options ranging from strong agreements to strong disagreement. The sum of the ratings for the 15 items for each individual surveyed is between 15 and 75, with higher values indicating a higher degree of job stress. Suppose that a similar approach, using a 20-item scale with a 1-5 response options, was used to measure the job stress of individuals for 15 randomly selected real estate agents, 15 architects, and 15 stockbrokers.

Use a = .05 to test for any significant differences in job stress among the three professions.

!! Explain the difference between the test of a difference between two means using independent variables and the test of a difference between two mean with dependent variables (Matched Samples)