You are a Human Resources Specialist considering using a test of mechanical ability to help select machine operators in your manufacturing facility. In order to conduct a validity study, you have collected the following data on your current employees.
Employee ID Test Score Job Performance Rating
A 55 61
B 79 72
C 59 69
D 81 89
E 62 52
F 70 75
G 80 61
H 89 79
I 92 90
J 60 55
K 63 85
L 64 87
M 69 70
N 75 90
O 84 67
P 77 84
Q 62 72
R 85 70
S 55 60
T 66 67
1. Draw a scatterplot of these data. What does the scatterplot tell you about the nature of the relationship between the test and the performance ratings?
2. A correlational analysis was conducted on these data. The correlation (r) between these two variables is .47. What does the correlation tell you about the nature of the relationship between the test and the performance ratings?
3. A regression analysis was conducted. The regression equation is Y' = 38.34 + .482X. Plot the regression line on the scatterplot. (Hint: The regression equation is the equation for a straight line. The total distance between each of the data points and the line is at its minimum, so the regression line is the line of best fit.)
Y' = a + bX, where
Y' = predicted score of the criterion variable
a = Y intercept
b = slope (sometimes called regression weight or regression coefficient)
X = observed score of the predictor variable
4. You have determined that a machine operator's acceptable level of job performance is at least 70. What would be a reasonable cut-off score on the predictor? (That is, what is the minimum score on the test of mechanical ability for an applicant score to be considered for a job as a machine operator)?
5. What kind of validity study is this?
