STAT 1350, Quiz #9, Summer 2014 Name _______________________________________

1. The correlation between the heights of fathers and the heights of their (adult) sons is
r = 0.52. This tells us that

A) taller-than-average fathers tend to have taller-than-average sons.
B) taller-than-average fathers tend to have shorter-than-average sons.
C) sons are, on the average, taller than their fathers.
D) 52% of all sons are taller than their fathers.
E) there is almost no connection between heights of fathers and sons.
Ans: A

2. Which of the values below is impossible for the descriptive measure in question?
A) r = –1.25 D) Both A and C are correct.
B) = –0.2 E) Both B and C are correct.
C) s = –3.4
Ans: D

3. A study found correlation r = 0.43 between high school math grades (on a 0 to 100 scale) and income 10 years after high school. This means that
A) people with high math grades tend to have higher income than people with low math grades.
B) people with low math grades tend to have higher income than people with high math grades.
C) there is almost no association between math grades and income.
D) a mistake has been made because a correlation cannot be 0.43.
E) a mistake has been made because a correlation between math grades and income makes no sense.
Ans: A

4. Which of the statements does not contain a statistical blunder?
A) There is a strong negative correlation between a person’s sex and the amount that he or she pays for automobile insurance.
B) The mean height of young women is 64 inches, and the correlation between their heights and weights is 0.6 inches.
C) The correlation between height and weight for adult females is about r = 1.2.
D) All three prior statements contain blunders.
Ans: D

5-8. An education researcher measured the IQ test scores of 78 seventh-grade students in a rural school, and also their school grade point average (GPA) measured on a 12-point scale. Here is a graph of GPA versus IQ for these students:

5. The name for this kind of graph is a
A) histogram. B) bivariate plot. C) boxplot. D) scatterplot.
Ans: D

6. The IQ score of the student who has the lowest GPA is about
A) 103. B) 0.6. C) 72. D) 7.2.
Ans: A

7. The graph shows
A) a clear positive association. C) a clear negative association.
B) very little association. D) a skewed distribution.
Ans: A

8. One of these numbers is the correlation r between IQ score and GPA. Which is it?
A) r = 0.02 B) r = 0.63 C) r = 0.95 D) r = –0.63 E) r = –0.95
Ans: B

9. Consider the following data:

x 3 6 –7 1 –5
y –3 –6 7 –1 5

The correlation coefficient r is
A) 7.6. B) 0.0 C) 1.0. D) –0.6. E) –1.0.
Ans: E