STAT 2607 Review Problems Midterm
(Solutions are attached to the end)
1.
A Life Insurance
Company manager believes that the number of weekly sales concluded by
his salesmen can be predicted by the number of followup phone calls they make to their
clients.
He collected the following data on
20
salesmen.
Calls:
66 43 57 32 18 59 61 32 48 39 58 54 48 37 29 21 43 62 51 44
Sales:
20 15 18 12
2 21 18
8 14 12 17 16 13
9
9
5 12 18 17 14
where
a)
What is the response variable in this problem?
What is the explanatory (predictor)
variable?
b)
State the simple linear regression model for this problem, and give all the other
assumptions needed for a complete regression analysis.
c)
Find the least squares fitted line.
Which of the assumptions in (b), if any, are
required for this step?
d)
Give the interpretation of b
0
and b
1
for this problem
.
e)
Why would it not be appropriate, in this problem, to say that
b
0
estimates the
average value of
Y
when
X
equals
0?
f)
What does it mean when we say that
b
1
is an unbiased estimator of ?
Which of the
assumptions given in (b) are needed for this to be true?
Assuming that the SLR model hypothesized in (b) holds with no violation of the
assumptions
g)
Set up the ANOVA table.
h)
Test whether there is a significant linear relationship between sales and followup
phone calls.
Use the Ftest with
= .01.
α
i)
What is the estimated average increase in weekly sales for each extra followup
phone call?
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 Spring '10
 waynehorn
 Statistics, Regression Analysis, weekly sales, followup phone calls

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