In Chapter 5, Exercise 9, we studied the variability of crime rates and police expenditures in the eastern and Midwestern United States. We’ve now been asked to investigate the hypothesis that the number of crimes is related to police expenditures per capita because states with higher crime rates are likely to increase their police force, thereby spending more on the number of officers on the street.
A. Construct a scatter diagram of the number of crimes and police expenditures per capita, with number of crimes as the predictor variable. What can you say about the relationship between these two variables based on the scatterplot?
B. Find the least-squares regression equation that predicts police expenditures per capita from the number of crimes. What is the slope? What is the intercept?
C. Calculate the coefficient of determination and provide an interpretation.
D. If the number of crimes increased by 100 for a state, by how much would you predict police expenditures capita to increase?
E. Does it make sense to predict police expenditures per capita when the number of crimes is equal to zero? Why or not?
2 answers
We do not have the data on either the crime rates or police expenditures.
If a set of data has mean=12 and standard deviation=3, then the coefficient of variation is [x]%
1 answer