QUESTION CONTINUED A study of students marks and how they a

QUESTION CONTINUED
: A study of students’ marks and how they are related to the hours of study they put in was conducted. A sample of 300 students was surveyed and asked to (anonymously) report their final mark (out of 100) in their introductory statistics class, as well as the number of hours per week they spent studying for it. A scatterplot of the data with a linear regression line included, as well as a residual plot from a simple linear regression on the results are given below:

f) If we fit a quadratic regression, the coefficient estimate for (Hours/Week)2 is –0.113 with a standard deviation of 0.093. Test whether the quadratic term is statistically significant. Would you suggest using the quadratic model over the linear one in this case?

8 8 10 40 50 60 70 80 Hours/Week of Study or Study Fimed Values

Solution