Question 1
Use the MLB data for this problem.
Chapter 13
Let attendance be the dependent variable and total team salary be the independent variable. Determine the regression equation and answer the following questions.
a. Draw a scatter diagram. From the diagram, does there seem to be a direct relationship between the two variables?
b. What is the expected attendance for a team with a salary of $100.0 million?
c. If the owners pay an additional $30 million, how many more people could they expect to attend?
d. At the .05 significance level, can we conclude that the slop of the regression line is positive? Conduct the appropriate hypothesis test.
e. What percentage of the variation in attendance is accounted for by salary?
f. Calculate the correlation between attendance and team batting average then between attendance and team ERA. Which is stronger?
Chapter 14
Let the number of games won be the dependent variable and the following variables be the independent variables: team batting average, team Earned Run Average (ERA), number of home runs, and whether the team plays in the National or American League.
a. Develop a correlation matrix. Which independent variables havestrong or weak correlations with the dependent variable? Do you see any problems with multicolinearity? Are you surprised that the correlation coefficient for ERA is negative?
b. Use Excel to calculate the multiple regression equation. How did you select the variables to include in the equation? Write out the regression equation. Interpret the R-square. Is the number of wins affected by whether the team plays in the National or American League?
Question 2
Use the Lincolnville School Bus (Buena) data set for this problem.
Chapter 13
Develop a regression equation that expresses the relationship between age of the bus and maintenance cost. The age of the bus is the independent variable.
a. Draw a scatter diagram. What does this diagram suggest as to the relationship between the two variables? Is it direct or indirect? Does it appear to be strong or weak?
b. Develop a regression equation. How much does an additional year add to the maintenance cost? What is the estimated maintenance cost for a 10-year-old bus?
c. Conduct a test of hypothesis to determine whether the slop of the regression line is greater than zero. Use the .05 significance level. Interpret your findings.
Chapter 14
Add a variable to change the type of engine (diesel or gasoline) to a qualitative variable. If the engine type is diesel, then set the variable to 0. If the engine type is gasoline, then set the qualitative variable to 1. Develop a regression equation using Excel with maintenance cost as the dependent variable and age, odometer miles, miles since last maintenance, and engine type as the independent variables.
a. develop a correlation matrix. Which independent variables have strong or weak correlations with the dependent variable? Do you see any problems with multicolinearity?
b. Use Excel to determine the multiple regression equation. How did you select the variables to include in the equation? How did you use the information in the correlation analysis? Show that your regression equation shows a significant relationship. Write out your equation and interpret the practical implications.