Name:

**1. A study is conducted to determine if one can predict the yield of a
crop based on the amount of yearly rainfall. What is the explanatory
variable in this study?**

**2. When are the variables said to be positively associated?**

**3. A researcher is interested in determining if one could predict the
score on a statistics exam from the amount of time spent studying
for the exam. In this study, what is the explanatory variable?**

**4. When water flows across farm land, some of the soil is washed away,
resulting in erosion. An experiment was conducted to investigate the
effect of the rate of water flow on the amount of soil washed away.
Flow is measured in liters per second and the eroded soil is
measured in kilograms. The data are given in the following table:**

**
**

Flow rate | .31 | .85 | 1.26 | 2.47 | 3.75 |

Eroded Soil | .82 | 1.95 | 2.18 | 3.01 | 6.07 |

What is the association between flow rate and amount of eroded soil?

**5. A student wonders if people of similar heights tend to date each
other. She measures herself, her dormitory roommate, and the women
in the adjoining rooms; then she measures the next man each woman
dates. Here are the data (heights in inches):**

Women | 66 | 64 | 66 | 65 | 70 | 65 |

Men | 72 | 68 | 70 | 68 | 74 | 69 |

**6. In baseball, power hitters are sometimes thought of as being large
and slow. Base stealers are often viewed as smaller and faster
players. If this is true, one might expect teams that hit many home
runs to have relatively few stolen bases and teams that steal many
bases to hit relatively few home runs. Suppose we wish to
investigate how well the number of home runs hit by a team predicts
the number of stolen bases by the team. What is the explanatory
variable?**

**7. Here is a scatterplot of the number of home runs versus the number
of stolen bases for each of the teams in the major leagues in 1993.
**

**8. Below is a scatterplot of number of home runs vs. number of stolen
bases for Major League teams in 1993. American League teams are
represented by x's and National League teams by circles.
**

**9. Which option is a scatterplot of the data in the following small,
artificial data set?
**

(response variable) | (explanatory variable) |
---|---|

**10. What does the correlation coefficient measure?**

**11. Which option is a plausible value for the correlation coefficient
between weight and MPG in the following scatterplot?
**

**12. Which of the following statements is true?**

**13. What is the correlation r for the data in the following small,
artificial data set?
**

(response variable) | (explanatory variable) |
---|---|

**14. For which of the following small data sets is the correlation r
between the x and y values equal to -1.0?**

x: 1 2 3

y: 2 4 6

x: 1 2 3

y: 3 2 1

x: 1 2 3

y: -3 -2 -1

x: 1 2 3

y: 1 2 3

**15. Which of the following statements is correct?**

**16. Which of the following statements is correct?**

**17. Two Olympic gymnasts tie on every event, each always getting the
exact same score as the other. What is the correlation between the
scores of these contestants?**

**18. Consider the following scatterplot of amounts of CO (carbon
monoxide) and NOX (nitrogen oxide) in grams per mile driven, in the
exhausts of cars. The least squares regression line has been drawn
in the plot.
**

**19. In the above scatterplot, the slope of the least squares line
fitted to these data would be which of the following?**

**20. In the above scatterplot, the least squares line would predict
that a car which emits 10 grams of CO per mile driven would emit how
many grams of NOX per mile driven?**

**21. If removing an observation from a data set would have a marked
change on the position of the least-squares regression line fit to
the data, what is the point called?**

**22. In regression, the residuals are which of the following?**

**23. What does the squared correlation coefficient, r ^{2}, measure?**

**24. Below are the Olympic gold medal performances in the men's high jump
from 1948 to 1984. High jump heights are in inches.
**

High jump | Year |
---|---|

1948 | |

1952 | |

1956 | |

1960 | |

1964 | |

1968 | |

1972 | |

1976 | |

1980 | |

1984 |

Referring to the above data, predicting the winning high jump height in the year 2200 using the regression equation given is an example of what?

**25. Suppose the correlation between two variables x and y is due to the
fact that both are responding to changes in some unobserved third
variable. What is this due to?**