A study of the top MBA programs attempted to predict the average starting salary (in $1000's) of graduates of the program based on the amount of tuition (in $1000's) charged by the program and the average GMAT score of the program's students. The results of a regression analysis based on a sample of 75 MBA programs is shown below:
Least Squares Linear Regression of Salary
Predictor
Variables Coefficient Std Error T P VIF
Constant -203.402 51.6573 -3.94 0.0002 0.0
Gmat 0.39412 0.09039 4.36 0.0000 2.0
Tuition 0.92012 0.17875 5.15 0.0000 2.0
The model was then used to create 95% confidence and prediction intervals for y and for E(Y) when the tuition charged by the MBA program was $75,000 and the GMAT score was 675. The results are shown here:
95% confidence interval for E(Y): ($126,610, $136,640)
95% prediction interval for Y: ($90,113, $173,160)
Which of the following interpretations is correct if you want to use the model to estimate E(Y) for all MBA programs?
◦ We are 95% confident that the average of all starting salaries for graduates of all MBA programs that charge $75,000 in tuition and have an average GMAT score of 675 will fall between $90,113 and $173,16,30.
◦ We are 95% confident that the average starting salary for graduates of a single MBA program that charges $75,000 in tuition and has an average GMAT score of 675 will fall between $90,113 and $173,16,30.
◦ We are 95% confident that the average of all starting salaries for graduates of all MBA programs that charge $75,000 in tuition and have an average GMAT score of 675 will fall between $126,610 and $136,640.
◦ We are 95% confident that the average starting salary for graduates of a single MBA program that charges $75,000 in tuition and has an average GMAT score of 675 will fall between $126,610 and $136,640.
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