Thompson Machine Works purchased several new, highly sophisticated machines. The production department needed some guidance with respect to qualifications needed by an operator. Four variables were listed.
X1 = Length of time employee was a machinist
X2 = Mechanical aptitude test score
X3 = Prior on -the-job rating
X4 = Age
Performance on the machine is designated Y
The following are the results of the regression analysis;
Independent
Variables Coefficient t-stat
Intercept 11.600 2.95
X1 0.400 1.23
X2 0.286 3.71
X3 0.112 4.10
X4 0.002 1.86
a. Write out the multiple regression equation.
b. How many independent variables are there?
c. Assuming the sample size was very large (the degrees of freedom is equal to 100), would you consider eliminating any of the independent variables?