Question 4 Beachcomber Ltd in a local car dealership that sells used and new vehicles. The manager of the company wants to know how different variables affect the sales of his vehicles. A random...

Question 4
Beachcomber Ltd in a local car dealership that sells used and new vehicles. The manager of the
company wants to know how different variables affect the sales of his vehicles. A random sample of
yearly data was taken with the view to testing the model:
SALES=?+?AGE+?MIL+?ENG
Where SALES= amount that a vehicle is sold for($000’s), AGE = age of the vehicle, MIL= the total
mileage of the vehicle at the point of sale and ENG = the size of the engine. The sample of data was
processed using MINITAB and the following is an extract of the output obtained:
The regression equation is *****
Predictor Coef StDev t-ratio p-value
Constant 1.7586 0.2525 6.9648 0.0000
AGE 0.2124 0.3175 * 0.5042
MIL -0.7527 0.3586 -2.0991 **
ENG 4.8124 0.6196 7.7664 0.0000
Analysis of Variance
Source DF SS MS F p
Regression 3 413.1291 138.7097 *** 0.00
Error 50 457.7607 2.2888
Total 53
a) What is dependent and independent variables?
b) Fully write out the regression equation
c) Fill in the missing values ‘*’, ‘**’, and ‘***’.
d) Hence test whether ? is significant. Give reasons for your answer.
e) Perform the F Test making sure to state the null and alternative hypothesis.
f) Given an interpretation of the term “R-sq” and comment on its value.