In: Statistics and Probability
Pursuing an MBA is a major personal investment. Tuition and expenses associated with business school programs are costly, but the high costs come with hopes of career advancement and high salaries. A prospective MBA student would like to examine the factors that impact starting salary upon graduation and decides to develop a model that uses program per-year tuition as a predictor of starting salary. Data were collected for 37 full-time MBA programs offered at private universities. The data are stored in the accompanying table. Complete parts (a) through (e) below.
a. Construct a scatter plot.
b. Assuming a linear relationship, use the least-squares method to determine the regression coefficients b0 and b1.
c. Interpret the meaning of the slope, b1, in this problem.
d. Predict the mean starting salary upon graduation for a program that has a per-year tuition cost of $47,424.
e. What insights can be obtained about the relationship between program per-year tuition and starting salary upon graduation?
| Program Per-Year Tuition ($) | Mean Starting Salary Upon Graduation ($) | 
| 62525 | 155817 | 
| 67451 | 152357 | 
| 67749 | 149035 | 
| 67666 | 144735 | 
| 66779 | 138899 | 
| 65528 | 152385 | 
| 65695 | 151892 | 
| 67655 | 151383 | 
| 64351 | 135432 | 
| 63923 | 141959 | 
| 67172 | 143153 | 
| 60574 | 145089 | 
| 61936 | 139567 | 
| 56822 | 135936 | 
| 53789 | 127037 | 
| 54703 | 116149 | 
| 56016 | 124588 | 
| 50732 | 128107 | 
| 52677 | 129467 | 
| 50944 | 121455 | 
| 47172 | 115002 | 
| 47340 | 110982 | 
| 48454 | 111045 | 
| 44833 | 106917 | 
| 36539 | 81620 | 
| 48766 | 79609 | 
| 47016 | 101254 | 
| 51112 | 74476 | 
| 37992 | 88178 | 
| 34391 | 76630 | 
| 43591 | 74766 | 
| 43030 | 52071 | 
| 50032 | 65298 | 
| 33704 | 103286 | 
| 23853 | 54156 | 
| 42047 | 81971 | 
| 39597 | 53127 | 
| Ʃx = | 1944156 | 
| Ʃy = | 4214830 | 
| Ʃxy = | 232985715420 | 
| Ʃx² = | 106996780762 | 
| Ʃy² = | 517682716166 | 
| Sample size, n = | 37 | 
| x̅ = Ʃx/n = 1944156/37 = | 52544.75676 | 
| y̅ = Ʃy/n = 4214830/37 = | 113914.3243 | 
| SSxx = Ʃx² - (Ʃx)²/n = 106996780762 - (1944156)²/37 = | 4841576645 | 
| SSyy = Ʃy² - (Ʃy)²/n = 517682716166 - (4214830)²/37 = | 37553204574 | 
| SSxy = Ʃxy - (Ʃx)(Ʃy)/n = 232985715420 - (1944156)(4214830)/37 = | 11518498299 | 
a)

b)
Slope, b1 = SSxy/SSxx = 11518498298.9189/4841576644.81081 = 2.37908
y-intercept, b0 = y̅ - b1* x̅ = 113914.32432 - (2.37908)*52544.75676 = -11093.86
Regression equation :
ŷ = -11093.857 + (2.3791) x
c)
As the value of program per-year tuition increases by a unit the value Mean Starting Salary Upon Graduation increases by 2.3791 on average.
d)
Predicted value of y at x = 47424
ŷ = -11093.857 + (2.3791) * 47424 = 101731.6342
e)
Mean starting salaries upon graduation tend to be higher among programs with higher per-year tuitions.