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AP Statistics / Mr. Hansen |
Name: _________________________ |
Quiz
on Chapter 14
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Open book, open notes. Time limit: 20 minutes (30
minutes for extended time). |
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Consult the graph and residual plot on p.459 of the Barron’s review book. Note that the horizontal axis of the residual plot is different from what you might expect, but the plot is still valid because of the linear relationship that is established between explanatory and response variables. |
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1. |
State the least-squares
regression line and identify your variables. |
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2. |
Estimate the number of rail
carloads in year 1968 (note: regression equation uses 2-digit years). Show
your work. |
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3. |
Pretend that the third and
fifth columns of the table are blanked out. Calculate the standard error of
the slope, showing your work. |
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4.(a) |
What requirement must the s.d. of the residuals satisfy in order to make a linear
regression t test valid? Do these
residuals satisfy that requirement? |
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(b) |
What other two requirements
must be met in order to make a linear regression t test valid? Although we do not have the raw data to enable you
to check these assumptions, explain how you would check them if you had
access to the raw data. |
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5. |
Assume that everything in
#4 is valid. Perform a t-test (show
all remaining steps) to see whether there is strong evidence of a negative
linear correlation. Use reverse side. |