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The following tables of correlation coefficients were created during a validation study conducted on assembly-line workers in a medium-sized workplace. Fifty assembly-line employees completed a general cognitive ability test and a job knowledge test, as well as a personality inventory assessing a trait called “need for achievement,” which is abbreviated “nAch.” High scores on the two tests and the personality inventory indicate greater amounts of each construct. The cost per applicant for each test is indicated in the tables. As part of the study, job performance data for each employee was also collected on three important dimensions of assembly line performance: error rates, speed of assembly, and teamwork. Higher scores on the performance dimensions indicate higher levels of each job performance dimension. Assume the reliability of each of the tests was satisfactory. Correlation coefficients are statistically significant if p<.05. Because the firm hires several hundred assemblers a year, it is concerned with minimizing selection costs; yet it also wants to maximize assembly line productivity. Answer the questions using the data in the tables below.

Cognitive Ability Test Cost: \$3.00 per applicant
Correlation with speed: rxy = .20
Correlation with error rates: rxy = .40*
Correlation with teamwork: rxy = .10
Correlation with nAch inventory: rxy = .05
Correlation with Job Knowledge test: rxy = .80*

Need for Achievement Inventory Cost: \$3.00 per applicant
Correlation with speed: rxy = .35*
Correlation with error rates: rxy = .40*
Correlation with teamwork: rxy = -.20
Correlation with Cognitive Ability test: rxy = .05
Correlation with Job Knowledge test: rxy = .10

Job Knowledge Test Cost: \$10.00 per applicant
Correlation with speed: rxy = .10
Correlation with error rates: rxy = .35*
Correlation with teamwork: rxy = .15
Correlation with Cognitive Ability test: rxy = .80*
Correlation with nAch inventory: rxy = .10

* indicates p< .05

a) Given this information, which predictors would you use to select assembly line employees? Make sure you briefly explain your reasoning.

b) Would additional predictor tests be useful in helping to predict job performance? If so, then what types of predictors would you consider using? Briefly explain your reasoning.