AP Statistics / Mr. Hansen |
Name: _______________________________________ |
11/9/2006 |
Mr. Hansen’s use only (bonus point for spare batteries):
_______ |
Quest through p. 276 in text, Version 2
Please read:
Calculator is OK throughout. However,
per your vote, no written or computer-printed notes are permitted today. Scoring
is 5 points per question with little or no partial credit (70 points total).
1. |
In an exponential
regression, your calculator reports r2
= 0.841. Which of the following is a true statement? |
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(A) Approximately 84% of
the variation in y can be explained
by the variation in x. (B) Approximately 84% of
the variation in log y can be
explained by the variation in x. (C) Approximately 91.7% of
the variation in y can be explained
by the variation in x. (D) Approximately 91.7% of the
variation in log y can be explained
by the variation in x. (E) Approximately 70.7% of
the variation in y can be explained
by the variation in x. |
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2. |
What name is given to r2 in the LSRL setting? |
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(A) regression coefficient (B) linear regression
coefficient (C) correlation coefficient (D) linear correlation
coefficient (E) coefficient of
determination |
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3. |
A scatterplot
shows an almost perfect linear relationship between x and y. The r2 value is close to 1, and
the residual plot shows no patterns. Can we infer that a change in y causes a change in x? |
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(A) No, since it is more
likely (statistically speaking) that a change in x causes a change in y. (C) No, unless y represents the control group in a
controlled experiment. (D) No, since both x and y could be affected by a lurking variable. |
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4. |
“Person on the street”
interviews, in which a newspaper, radio, or TV reporter gathers opinions from
passersby in an attempt to illustrate a current-events story with lively
quotes, are . . . |
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(A) anecdotal data (B) subject to voluntary
response bias (C) subject to undercoverage bias since many people are stuck in
buildings during the working day (D) subject to response
bias (E) all of the above |
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5. |
In a hypothetical survey of
attitudes toward lunch, suppose that the mean lunch rating by freshmen (on a scale
of 0 to 10, 10 being highest) is 6.2, but for seniors, the mean rating is
only 3.1. Can we conclude that freshmen (on average) like lunch twice as much
as seniors do? |
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(A) Yes, but only if the
sample sizes were fairly large. |
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(B) Yes, but only if the
sample sizes were fairly large and each sample was an SRS. |
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(C) No, since there is
likely to be a great deal of response bias. |
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(D) No, since the scale is
not an ordinal scale. |
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(E) No, since the scale is
not a ratio scale. |
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For questions 6-9, consider
the following actual data (American
Sociological Review, 1981) concerning 326 criminal cases in which the
death penalty was considered after the perpetrator had been convicted. The 326
defendants consisted of 160 whites and 166 blacks. Of the 160 white
defendants, 151 of them were found guilty of murdering white victim(s) and 9
were found guilty of murdering black victim(s). Of the 166 black defendants,
63 of them were found guilty of murdering white victim(s) and 103 were found
guilty of murdering black victim(s). |
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6. |
Compute the percentage of
white convicts in this study (out of 160 total) who
received the death penalty. ____ Compute the percentage of black convicts in
this study (out of 166 total) who received the death
sentence. ____ Which death penalty rate is higher, the one for white convicts
or the one for black convicts? _____________ |
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7. |
Given that the victim was white,
prove that black defendants were more likely to receive the death penalty
than white defendants were. (Show the numbers and/or percentages that you are
using.) |
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8. |
Given that the victim was
black, prove that black defendants were more likely to receive the death
penalty than white defendants were. (Show the numbers and/or percentages that
you are using.) |
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9. |
What topic from the textbook
is illustrated by questions 5, 6, and 7, considered as a group? |
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10. |
Give an example of a
nominal scale that has more than 2 possible outcomes and is not ordinal. |
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11. |
Why does any reputable
survey reported in print always include the wording of the question that was
used? |
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12. |
Explain what is meant by
the term push polling. |
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13. |
State what is meant by a difference
between experimental and control groups that is statistically significant. |
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____________________________________________ |
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14. |
Using the phrase statistically significant or statistical significance, explain what
constitutes statistical proof of cause and effect. |