5 Refer to the previous exercise Table 13.16 shows a SPSS printout from fitting the model allowing interaction. where NEWSIZE refers to the cross-product term. TABLE 13.16 R Square Adjusted R Square .8675 .8630 Standard Error 16.3509 Analysis of Variance DF Sum of Squares Regression 3 155811.60588 Mean Square 51937.20196 Residual 89 23794.26079 267.35124 F = 194.26579 Signif .0000 = Variables in the Equation Variable B SE B Beta T Sig T NEW -31.826 14.818 -.332 -2.148 .0344 SIZE 66.604 3.694 .792 18.033 .0000 NEWSIZE 29.392 8.195 .571 3.587 .0005 (Constant) -16.600 6.210 -2.673 -0089

a) Interpret the parameter estimates. Report the lines relating Y to X for (i) new homes. (ii) older homes.

b) For the interaction model. find the predicted selling price for a home of 3000 square feet that is (i) new. (ii) older. Compare results to those in Problem 13.4(c).

c) For the interaction model. find the predicted selling price for a home of 1500 square feet that is (i) new, (ii) older Compaing results to (b). explain how the difference in predicted pnces between new and older homes changes as size of home increases.

d) Test for interaction between size of home and whether it is new Interpret. How would you summarize these data?