Chapter 13.3, Problem 21PB

Study time help GPA? Refer to the previous exercise.

1. a. Report and interpret the P-value for testing the hypothesis that the population slope coefficient for study time equals 0.
2. b. Find a 95% confidence interval for the true slope for study time. Explain how the result is in accord with the result of the test in part a.
3. c. Does the result in part a imply that in the corresponding population, study time has no association with college GPA? Explain. (Hint: What is the impact of also having HSGPA in the model?)

13.20 Predicting GPA For the 59 observations in the Georgia Student Survey data file on the book’s website, the result of regressing college GPA on high school GPA and study time follows.

Regression Equation

CGPA = 1.126 + 0.643 HSGPA + 0.0078 Studytime

Coefficients

1. a. Explain in nontechnical terms what it means if the population slope coefficient for high school GPA equals 0.
2. b. Show all steps for testing the hypothesis that this slope equals 0.