Thompson Photo Works purchased several new, highly sophisticated processing machines. The production department needed some guidance with respect to qualifications needed by an operator. Is age a factor? Is the length of service as an operator (in years) important? To evaluate the factors needed to estimate performance on the new processing machines, four variables were selected: x₁ = Length of time an employee was in the industry x₂ = Mechanical aptitude test score x₃ = Prior on-the-job rating x₄ = Age Performance on the new machine is designated y. Thirty employees were randomly selected and data were collected for each of the variables. A few results follow:

Thirty employees were randomly selected and data 'were collected for each of the variables. A few results follow