Question 1

Recently,an automobile insurance company performed a study of a random sample of 15 of its customers to determine if there is a positive relationship between the number of miles driven and the age of the driver.The sample correlation coefficient is r = .38.Given this information,and assuming that the test is to be performed at the .05 level of significance,which of the following is the correct test statistic?

Accepted Answer

A) t = 1.4812 
B) t = 1.7709 
C) z = 2.114 
D) t = 1.74

Question 2

A recent study of 15 shoppers showed that the correlation between the time spent in the store and the dollars spent was 0.235.Using a significance level equal to 0.05,which of the following is the test statistic for testing whether the true population correlation is equal to zero?

Accepted Answer

A) t = 0.245 
B) t = 1.76 
C) t = 2.1604 
D) t = 0.872

Question 3

If a set of data contains no values of x that are equal to zero,then the regression coefficient,b0,has no particular meaning.

Accepted Answer

A) True 
 B)False

Question 4

A study was recently conducted by Major League Baseball to determine whether there is a correlation between attendance at games and the record of home team's opponent.In this study,the dependent variable would be the record of the home team's opponent.

Accepted Answer

A) True 
 B)False

Question 5

When using regression analysis for descriptive purposes,which of the following is of importance?

Accepted Answer

A) The size of the regression slope coefficient 
B) The sign of the regression slope coefficient 
C) The standard error of the regression slope coefficient 
D) All of the above

Question 6

Use the following regression results to answer the question below.  How many observations were involved in this regression?

Accepted Answer

A) 7 
B) 8 
C) 9 
D) 10

Question 7

The following regression output is available.Notice that some of the values are missing.  Given this information,what was the sample size used in the study?

Accepted Answer

A) 8 
B) 18 
C) 9 
D) 16

Question 8

A random sample of two variables,x and y,produced the following observations:  Test to determine whether the population correlation coefficient is negative.Use a significance level of 0.05 for the hypothesis test.

Accepted Answer

A) Because t = -4.152 < -1.9432,reject the null hypothesis.Because the null hypothesis is rejected,the sample data does support the hypothesis that there is a negative linear relationship between x and y. 
B) Because t = -4.152 < -1.9432,do not reject the null hypothesis.Because the null hypothesis is not rejected,the sample data support the hypothesis that there is a negative linear relationship between x and y. 
C) Because t = -9.895 < -1.9432,reject the null hypothesis.Because the null hypothesis is rejected,the sample data does support the hypothesis that there is a negative linear relationship between x and y. 
D) Because t = -9.895 < -1.9432,do not reject the null hypothesis.Because the null hypothesis is not rejected,the sample data support the hypothesis that there is a negative linear relationship between x and y.

Question 9

Explain what the correlation coefficient measures and some detail of the key issues associated with it.Be sure to also discuss the concept of spurious correlation.

Accepted Answer

The answer of Explain what the correlation coefficient measures and...

Question 10

Given a sample of size n = 15 and a sample correlation of r = 0.7,the value of the test statistic for conducting a hypothesis test of the correlation is t = 3.53.

Accepted Answer

A) True 
 B)False

Question 11

The difference between a scatter plot and a scatter diagram is that the scatter plot has the independent variable on the x-axis while the independent variable is on the Y-axis in a scatter diagram.

Accepted Answer

A) True 
 B)False

Question 12

Which of the following statements is true?

Accepted Answer

A) The interval estimate for predicting a particular value of y given a specific x will be narrower than the interval estimate for the average value of y given a particular x. 
B) The higher the r-square value,the wider will be the prediction interval based on a simple linear regression model. 
C) The prediction interval generated from a simple linear regression model will be narrowest when the value of x used to generate the predicted y value is close to the mean value of x. 
D) The prediction interval generated from a simple linear regression model will be widest when the value of x used to generate the predicted y value is close to the mean value of x.

Question 13

If the correlation coefficient for two variables is computed to be a -0.70,the scatter plot will show the data to be downward sloping from left to right.

Accepted Answer

A) True 
 B)False

Question 14

Use the following regression results to answer the question below.  Which of the following is true?

Accepted Answer

A) The correlation between x and y must be approximately 0.8851. 
B) The correlation between x and y must be approximately -0.8851. 
C) The correlation between x and y must be approximately 0.7835. 
D) The correlation between x and y must be approximately -0.7835.

Question 15

Which of the following statements is true?

Accepted Answer

A) If the confidence interval estimate for the regression slope coefficient crosses over zero,the average change in y for a one-unit change in x may be zero. 
B) If the regression slope coefficient is very close to zero,this means that the relationship between the x and y variables is statistically insignificant. 
C) A statistically significant regression slope coefficient indicates that for a one-unit change in y there will be a positive change in x by an amount equal to the regression slope coefficient. 
D) It is acceptable to make predictions for y using x values that are outside the range of the data that was used in the regression.

Question 16

Which of the following statements is correct?

Accepted Answer

A) A scatter plot showing two variables with a positive linear relationship will have all points on a straight line. 
B) The stronger the linear relationship between two variables,the closer the correlation coefficient will be to 1.0. 
C) Two variables that are uncorrelated with one another may still be related in a nonlinear manner. 
D) All of the above are correct.

Question 17

A recent study of 15 shoppers showed that the correlation between the time spent in the store and the dollars spent was 0.235.Using a significance level equal to 0.05,which of the following is the appropriate null hypothesis to test whether the population correlation is zero?

Accepted Answer

A) H0 : r = 0.0 
B) H0 : ρ = 0.0 
C) H0 : μ = 0.0 
D) H0 : ρ ≠ 0

Question 18

In a university statistics course a correlation of -0.8 was found between numbers of classes missed and course grade.This means that the fewer classes students missed,the higher the grade.

Accepted Answer

A) True 
 B)False

Question 19

If the correlation of x and y is -0.65,then coefficient of determination is -0.4225.

Accepted Answer

A) True 
 B)False

Question 20

In simple linear regression,the t-test for the slope and the F-test are both conducting the same hypothesis test.

Accepted Answer

A) True 
 B)False

Exam 14: Introduction to Linear Regression and Correlation Analysis

A recent study of 15 shoppers showed that the correlation between the time spent in the store and the dollars spent was 0.235.Using a significance level equal to 0.05,which of the following is the test statistic for testing whether the true population correlation is equal to zero?

If a set of data contains no values of x that are equal to zero,then the regression coefficient,b₀,has no particular meaning.

A study was recently conducted by Major League Baseball to determine whether there is a correlation between attendance at games and the record of home team's opponent.In this study,the dependent variable would be the record of the home team's opponent.

When using regression analysis for descriptive purposes,which of the following is of importance?

Use the following regression results to answer the question below. How many observations were involved in this regression?

The following regression output is available.Notice that some of the values are missing. Given this information,what was the sample size used in the study?

A random sample of two variables,x and y,produced the following observations: Test to determine whether the population correlation coefficient is negative.Use a significance level of 0.05 for the hypothesis test.

Explain what the correlation coefficient measures and some detail of the key issues associated with it.Be sure to also discuss the concept of spurious correlation.

Given a sample of size n = 15 and a sample correlation of r = 0.7,the value of the test statistic for conducting a hypothesis test of the correlation is t = 3.53.

The difference between a scatter plot and a scatter diagram is that the scatter plot has the independent variable on the x-axis while the independent variable is on the Y-axis in a scatter diagram.

Which of the following statements is true?

If the correlation coefficient for two variables is computed to be a -0.70,the scatter plot will show the data to be downward sloping from left to right.

Use the following regression results to answer the question below. Which of the following is true?

Which of the following statements is true?

Which of the following statements is correct?

A recent study of 15 shoppers showed that the correlation between the time spent in the store and the dollars spent was 0.235.Using a significance level equal to 0.05,which of the following is the appropriate null hypothesis to test whether the population correlation is zero?

In a university statistics course a correlation of -0.8 was found between numbers of classes missed and course grade.This means that the fewer classes students missed,the higher the grade.

If the correlation of x and y is -0.65,then coefficient of determination is -0.4225.

In simple linear regression,the t-test for the slope and the F-test are both conducting the same hypothesis test.