Question 1

A sociologist is interested in how family income (in 1,000s of dollars) predicts number of books in the home. He produces a regression equation stating that Y = 50 + 0.25(X).
-Which of the following would be an accurate interpretation of this finding?

Accepted Answer

A)  For each additional $1,000 of income, families have an average of 50 additional books. 
B)  For each additional $50 of income, families gain an average of 0.25 extra books. 
C)  For each additional 0.25 books, families have an extra $50. 
D)  For each additional $1,000 of income, families have an average of 0.25 additional books.

Question 2

A researcher asked a sample of dual-wage-earner families about the percentage of the family budget that is contributed by the wife's job (Y), and about the total number of children (X). Pearson's r for this relationship is -0.34. Which of the following is an appropriate interpretation of these results?

Accepted Answer

A)  Every additional child lowers the economic well-being of the family. 
B)  For every additional child, the wife must work longer hours. 
C)  As the number of children increases, the percentage of the budget contributed by the wife decreases. 
D)  For every dollar contributed by the wife, the number of children increases by 0.34.

Question 3

In what sense does "Y-predicted" provide only an "educated guess" of Y?

Accepted Answer

A)  Exact predictions of Y are extremely rare: exactness is achieved only when the relationship between X and Y is perfectly linear. 
B)  Y-predicted typically loses precision when X and Y are both interval-ratio variables; it is more exact when at least one variable is measured on a nominal scale. 
C)  Y-predicted predicts Y without taking into account values of X. 
D)  Y-predicted is based on Y's overall mean and ignores the conditional mean of Y.

Question 4

Explain what is meant by a "linear relationship" and provide a brief example of such an association.

Accepted Answer

The answer of Explain what is meant by a "linear...

Question 5

A researcher is interested in the relationship between years of schooling and number of alcoholic drinks consumed per week. What would be an appropriate measure of association for these two variables?

Accepted Answer

A)  phi 
B)  Kendall's tau-b 
C)  Pearson's r 
D)  lambda

Question 6

What are the two components of variation used in calculating the coefficient of determination?

Accepted Answer

A)  explained variation and unexplained variation 
B)  sampling variation and population variation 
C)  standard variation and homoscedastic variation 
D)  conditional variation and linear variation

Question 7

When can a perfect association between variables be seen on a scatterplot?

Accepted Answer

A)  when the regression line forms a right angle at its intersection with the X axis 
B)  when the regression line is parallel to the X axis 
C)  when all dots lie an equal distance from the regression line 
D)  when all dots lie on the regression line

Question 8

A regression line from a sample of high-school students shows that the association between number of days drunk per month and achievement test scores is -5.5. Which of the following could be concluded from this result?

Accepted Answer

A)  that students who drink once per month get scores 5.5 points higher than those who drink every day 
B)  that scores decrease by 5.5 points for every day drunk per month 
C)  that students who never drink score 5.5 on the test 
D)  that there is a moderate association between drinking and test performance

Question 9

The Pearson's r correlation between pets owned during one's lifetime and longevity is zero. What is the value of the slope (b)?

Accepted Answer

A)  -1.00 
B)  0 
C)  0.50 
D)  1.00

Question 10

The association between number of Facebook friends and screen time per day has an r2 value of 0.18. Which of these statements is the best interpretation of this statistic?

Accepted Answer

A)  There is a moderate, positive relationship between Facebook friends and screen time. 
B)  There is a strong, negative relationship between Facebook friends and screen time. 
C)  There is a weak, linear relationship between Facebook friends and screen time. 
D)  Screen time explains 18% of the total variance in number of Facebook friends.

Question 11

A basketball coach claims that all variability in free-throw shooting accuracy can be explained by hours of foul shot practice spent per season. What is he claiming about the value of r2?

Accepted Answer

A)  It is equal to 0. 
B)  It is equal to 1. 
C)  It is equal to 100. 
D)  It is equal to 1000.

Question 12

Suppose the predicted value of Y in a regression equation is 10. X = 2 and b = 4. What would the Y intercept value be?

Accepted Answer

A)  1 
B)  2 
C)  4 
D)  20

Question 13

What is the best way to describe a slope that has a value close to zero?

Accepted Answer

A)  There is a weak effect of X on Y. 
B)  There is a moderate effect of X on Y. 
C)  There is a strong effect of X on Y. 
D)  It is impossible to say without knowing the coefficient of determination.

Question 14

What assumption about the nature of a relationship is necessary for testing Pearson's r for significance?

Accepted Answer

A)  The relationship must be positive. 
B)  The relationship must be linear. 
C)  The relationship cannot be homoscedastic. 
D)  The relationship can include only one interval-ratio variable.

Question 15

Which of the following is the null hypothesis when testing Pearson's r for significance?

Accepted Answer

A)  No difference exists between the sample and the population from which the sample was drawn. 
B)  No linear association exists between the variables in the sample. 
C)  No difference exists between the variables in the sample. 
D)  No linear association exists between the variables in the population from which the sample was drawn.

Question 16

A sociologist is interested in how family income (in 1,000s of dollars) predicts number of books in the home. He produces a regression equation stating that Y = 50 + 0.25(X).
-From this equation, how many books would we predict for a family with an income of $40,000?

Accepted Answer

A)  40 books 
B)  50 books 
C)  60 books 
D)  80 books

Exam 13: Hypothesis Testing and Measures of Association for Variables Measured at the Interval-Ratio Level

A sociologist is interested in how family income (in 1,000s of dollars) predicts number of books in the home. He produces a regression equation stating that Y = 50 + 0.25(X) . -Which of the following would be an accurate interpretation of this finding?