STAT 331/361/SYDE 334 Assignment 4
Due:
T
uesday
,
April
01
,
2008
in class
1.
This question refers to Q5 of Assignment 2 on an entrance test to n = 20 randomly selected
students from the new freshmen class. The response variable y is the GPA at the end of the
freshman year,
is the entrance test score,
is the score on orientation involvement and
is the athletic test score. Suppose that each of the 20 students also received an overall score,
based on all activities happened in the first week. The new data file is named
A4
data.txt
and can be downloaded from the course web page.
1
x
2
x
3
x
4
x
(a)
Fit a multiple regression model with all four predictors included in the model; discuss
possible multicollinearity problems for the model.
(b)
Calculate all four variance inflation factors (VIF). Do these VIFs agree or disagree with
your findings from part (a)?
2.
Refer to problem #3 in Assignment #3.
(a)
When you analyzed this data in assignment #3 you noticed that one point is extremely far
away from
the rest of the data. Perform some more residual checks (look at the leverages and
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 Winter '08
 YuliaGel
 Correlation Coefficient, Regression Analysis, Web page, Covariance matrix, entrance test score, athletic test score

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