To begin a stepwise multiple linear regression, you plot all of the inputs (independent factors x1-x5) with the output y. To perform a backward elimination stepwise regression, which variable should be entered first? a. x1 b. x2 c. x3 d. x4 e. x5

40 Bivariate Fit of y By x1 40 Bivariate Fit of y By x2 40 Bivariate Fit of y By x3 20,000 20,000 20,000 15,000 15,000 15,000 y 10,000 y 10,000 y 10,000 5,000 5,000 5,000 0 100 200 300 400 500 0 20,000 40,000 60,000 80,000 0 5,000 10,000 15,000 x1 x2 X3 Linear Fit Linear Fit Linear Fit Linear Fit Linear Fit Linear Fit y = -130.9707 + 34.220933*x1 y = 439.32991 + 0.2479645*x2 y = -90.75017 + 1.1234875*x3 Summary of Fit Summary of Fit Summary of Fit RSquare 0.973586 RSquare 0.892434 RSquare 0.974173 RSquare Adj 0.971825 RSquare Adj 0.885263 RSquare Adj 0.972451 Root Mean Square Error 937.4934 Root Mean Square Error 1891.852 Root Mean Square Error 927.0222 Mean of Response 4943.168 Mean of Response 4943.168 Mean of Response 4943.168 Observations (or Sum Wgts) 17 Observations (or Sum Wgts) 17 Observations (or Sum Wgts) 17 Analysis of Variance Analysis of Variance Analysis of Variance Parameter Estimates Parameter Estimates Parameter Estimates