Many chief executives have been under serious criticism from organized labor for the fat paychecks that they take home. An experiment was set up in which 15 observations were taken on the variables: Y = chief executives' pay (in thousands of dollars), X1 = firm's net profit (in millions of dollars), and X2 = number of employees (in thousands). Using excel, the following sample statistics were obtained: b1 = 0.1336, sb1 = 0.0424, b2 = -0.86, sb2 = 0.39.
a) Given that X2 is in the model, does X1 contribute to predicting the dependent variable at the .05 significance level?
b) Given that X1 is in the model, does X2 contribute to predicting the dependent variable at the .05 significance level?