8. The printouts in Table 13.18 show results of using SAS to fit four models to data from a study of the relationship between Ypercentage of adults voting, X = percentage of adults registered to vote. and racial-ethnic representation, for precincts in the state of Texas for a gubernatorial election Racial-ethnic representation of a precinct is the group (Anglo. black. or Mexican Amencan) having the strongest representation in a precinct A random sample of 40 precincts is selected after a particular election and classified by racial-ethnic representation

a) Report the prediction equation for the analysis of covan- ance model assuming no interaction Interpret the parameter estimates. Report the three racial-ethnic prediction equations

b) Report the prediction equation for the analysis of covariance model allowing inter- action. Interpret the parameter estimates Report the three racial-ethnic prediction equa- Lions, and compare them to the equations for the no interaction model. Interpret the nature of the predicted interaction

c) Test whether the regression lines relating Y and X for the three categories have the same slope Report the test statistic and P-value. and interpret.

d) Report the prediction equation between Y and X, ignanng racial-ethnic representa- tion. Interpret.

e) For the model assuming no interaction, test whether the regression lines between ) and X for the three groups are identical. Report the test statistic and P-value, and interpret.

f) For the model assuming no interaction. test whether the mean voting porcentages are equal for the three categories of racial-ethnic representation, controlling for percentage registered. Report the test statistic and P-value, and interpret. g) Report the test staustic and P-value for testing the null hypothesis that percentage vot- ing and percentage registered are independent, controlling for racial-ethnic representa- Lion Interpret