1. Here's some output from the Mountain View data, which offers information about houses in King County, Washington, including their saleprice, square footage, whether they have a mountain view of any of the mountain ranges in the area, and which of the three mountain ranges (Mt. Rainier, the Cascades or the Olympics) they have views of. Also included is the quality grade attached to the building, BLDGGRAD, in which a higher number indicates that the building is in better condition, which we'll just take as a quantitative variable. Here are regression results both with and without building grade: > MauntainviewMidterm View (MountainkiewMidterm > attach (Mountain ViewMidterm > Reg1 Reg2 summary (Reg1) Call: Residuals: Min formula = SALEPRIC~ SQFT + MTNVIEW) Coefficients: 1Q Median -1425948 110345 -40516 SALE PRIC-SQFT+MTNVIEW) SALEPRIC~SQFT+MTNVIEW+BLDGGRAD) = (Intercept) -125485.75 Call: (>|t|) summary_(Reg2) Estimate Std. Error t value --- SQFT MTNVIEW BLDGGRAD Residuals: Min 1Q Median -1311162 -100196 -36958 3Q Max 34161 4239452 formula = SALEPRIC~ SQFT + MTNVIEW + BLDGGRAD) 118.61 71472.73 107457.64 8527.46 -14.715 3 23 64 563 8856.68 9.395 Coefficients: Estimate Std. Error t value (>|t|) (Intercept) -830733.51 24755.28 -33.558 MauntainviewMidterm View (MountainkiewMidterm > attach (Mountain ViewMidterm > Reg1 Reg2 summary (Reg1) Call: Residuals: Min formula = SALEPRIC~ SQFT + MTNVIEW) Coefficients: 1Q Median -1425948 110345 -40516 SALE PRIC-SQFT+MTNVIEW) SALEPRIC~SQFT+MTNVIEW+BLDGGRAD) = (Intercept) -125485.75 Call: (>|t|) summary_(Reg2) Estimate Std. Error t value --- SQFT MTNVIEW BLDGGRAD Residuals: Min 1Q Median -1311162 -100196 -36958 3Q Max 34161 4239452 formula = SALEPRIC~ SQFT + MTNVIEW + BLDGGRAD) 118.61 71472.73 107457.64 8527.46 -14.715 3 23 64 563 8856.68 9.395 Coefficients: Estimate Std. Error t value (>|t|) (Intercept) -830733.51 24755.28 -33.558