Quiz 3.1 & 3.2 Review
AP Statistics
Name:
Often the percent of an animal species in the wild that survive to breed again is lower following a
successful breeding season. This is part of nature’s self-regulation, tending to keep population stable.
A study of merlins (small falcons) in northern Sweden observed the number of breeding pairs in an
isolated area and the percent of males (banded for identification) who returned the next breeding
season. Here are data for nine years:
1. Is there a clear explanatory variable and response variable in this setting? If so, tell which is
which. If not, explain why not.
2. Make a well-labeled scatterplot of these data.
3. How would you describe the form of the relationship?
4. Based on the scatterplot, do you expect the correlation to be positive or negative? Near  1 or not?
Explain.
5. Use your calculator to find the correlation r between number of breeding pairs and percent of males
returning. Do the data support the theory that a smaller percent of birds survive following a
successful breeding season? Explain.
6. How would r change if researchers had recorded the proportion (such as 0.82) of males who
returned instead of the percent (such as 82) who returned? Explain.
Chapter 3
Quiz 3.1&3.2
Quiz 3.1 Review
AP Statistics
Name:
We often describe our emotional reaction to social rejection as “pain.” A clever study asked whether
social rejection causes activity in areas of the brain that are known to be activated by physical pain. If
it does, we really do experience social and physical pain in similar ways. Subjects were first included
and then deliberately excluded from a social activity while changes in brain activity were measured.
After each activity, the subjects filled out questionnaires that assessed how excluded they felt. The
table below shows data for 13 subjects.
The explanatory variable is “social distress” measured by each subject’s questionnaire score
after exclusion relative to the score after inclusion. (So values greater than 1 show the degree of
distress caused by exclusion.) The response variable is change in activity in a region of the brain that is
activated by physical pain.
7. Use your calculator to construct a scatterplot of
these data. Describe what you see.
8. Find the equation of the least-squares line on your calculator. Record the equation below. Be sure
to define any variables used.
9. Interpret the slope of the least-squares line in context.
10.
Show how to calculate the residual for the individual with social distress score 2.01.
11. What would you predict for the brain activity level for an individual with social distress 3.10?
12. Interpret the value of r 2 from your calculator in the context of this problem.
Chapter 3
Quiz 3.1&3.2