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STAT 502 – Assignment #2
Coverage:
KKMN Chapters 47
Name:
____________________________
SCORE:
____ of 40
Homework Problems—These should be done individually!
#1.
(3 pts) Briefly explain the difference between the following two equations.
Do either of these
constitute a
complete
statement of the Simple Linear Regression model?
If not, what else is
needed?
0
1
0
1
ˆ
Y
b
b X
Y
X
=
+
= β +β
+ ε
#2.
(10 pts) Refer to KKMN 5.06 but ignore the questions in the text and answer the following
questions instead.
Also, the fitted regression equation is:
ˆ
646.48334 14.04105
y
x
=

.
a.
What is the fitted value (also called predicted value) corresponding to a AGE of 12.00?
b.
For the same adolescent with a AGE of 12.00, if the observed data point is an ATST of 500,
find the residual.
c.
Consider the data point in part (b).
An additional ATST is to be obtained for a new
observation at
x
= 12.
Would the ATST for the new observation also necessarily be 500?
Why or why not?
d.
A newborn baby would have an AGE of 0, what is the predicted value for a newborn baby?
Is this predicted value trustworthy?
Why or why not?
e.
If the AGE is increased by 5, how is the expected ATST affected?
f.
The standard error for the slope was found to be 1.36812.
An analyst concludes that the
regression is not significant since the slope, b
1
, is negative.
Do you agree/disagree with the
analyst? Comment and conduct any appropriate significance tests you feel appropriate in
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 Fall '08
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