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
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? [2]
b) Fully write out the regression equation [1]
c) Fill in the missing values ‘*’, ‘**’ , ‘***’and ‘***” [4]
d) Hence test whether ? is significant. Give reasons for your answer. [4]
e) Perform the F Test making sure to state the null and alternative hypothesis. [4]
f) Given an interpretation of the term “R-sq” and comment on its value. [2]
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