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    Regression analysis and confidence interval

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    1. David Gallano, a wine merchant, has collected opinions on grape wine quality from a sample of his customers. These customers tasted wine made from grapes grown in three regions of the country. They rated the wine quality on a scale of 1 (best) to 4 (worst). The following is the data obtained for customer quality rating of wine by grape-growing region.

    Quality Rating Growing Regions ----- Row Total
    I II III
    1 15 10 6 31
    2 7 13 12 32
    3 11 12 8 31
    4 3 8 15 26
    Column Total 36 43 41 120

    David wants to know whether quality ratings are or, are not independent of grape growing region. Can you conclude at a 95% confidence that the quality rating is independent of the grape-growing region?

    2. The chairperson of the marketing department at a university undertakes a study to relate the starting salary after graduation for marketing majors to overall grade point average (GPA). To do this, he/she identifies records of seven randomly selected recent marketing graduates. The results are:

    Marketing Graduates Starting salary in thousands of dollars GPA
    1 33.8 3.26
    2 29.8 2.60
    3 33.5 3.35
    4 30.4 2.86
    5 36.4 3.82
    6 27.6 2.21
    7 35.3 3.47

    Compute the equation of the regression line and interpret the results.

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    Solution Summary

    Step by step method for regression analysis is discussed here. Regression coefficients, coefficient of determination, scatter diagram and significance of regression model are explained in the solution.