11.4. Use software with the "2005 statewide crime" data file at the text Web site, with murder rate (number of murders per 100,000 people) as the response variable and with percent of high school graduates and the poverty rate (percentage of the population with income below the poverty level) as explanatory variables.

(a) Construct the partial regression plots. Interpret. Do you see any unusual observations?

(b) Report the prediction equation. Explain how to interpret the estimated coefficients.

(c) Redo the analyses after deleting the D.C.

observation. Describe the influence of this observation on the predicted effect of poverty rate. What does this tell you about how influential outliers can be?