Question 1

Which of the following is true?

Accepted Answer

A)  The confidence interval for the predicted mean value of y is always narrower than the prediction interval for an individual y when both are calculated for a given value of x. 
B)  The prediction interval for an individual y is always narrower than the confidence interval for the predicted mean value of y, when both are calculated for a given value of x. 
C)  The confidence interval of the slope is the same as the confidence interval for the predicted y. 
D)  The confidence interval for the predicted mean value of y is the same as the prediction interval for an individual y when both are calculated for a given value of x. 
E)  The width of the confidence interval for the predicted mean value of y is greater than that of the prediction interval for an individual y when both are calculated for a given value of x. 
A)  The confidence interval for the predicted mean value of y is always narrower than the prediction interval for an individual y when both are calculated for a given value of x. 
B)  The prediction interval for an individual y is always narrower than the confidence interval for the predicted mean value of y, when both are calculated for a given value of x. 
C)  The confidence interval of the slope is the same as the confidence interval for the predicted y. 
D)  The confidence interval for the predicted mean value of y is the same as the prediction interval for an individual y when both are calculated for a given value of x. 
E)  The width of the confidence interval for the predicted mean value of y is greater than that of the prediction interval for an individual y when both are calculated for a given value of x.

Question 2

Consider the following to answer the question(s) below:
A study was recently performed by the Canada Revenue Agency to determine how much tip income waiters and waitresses would make based on the size of the bill at the table. A random sample of bills and resulting tips was collected. These data and regression results are as follows:
    
-The value of the correlation coefficient is

Accepted Answer

A)  +0.9366. 
B)  - 0.9366. 
C)  +0.8773. 
D)  - 0.8773. 
E)  +0.8620. 
A)  +0.9366. 
B)  - 0.9366. 
C)  +0.8773. 
D)  - 0.8773. 
E)  +0.8620.

Question 3

Consider the following to answer the question(s) below:
A sales manager was interested in determining if there is a relationship between college GPA and sales performance among salespeople hired within the last year. A sample of recently hired salespeople was selected and the number of units each sold last month was recorded. Relevant data appear in the table below.
   Below are the scatterplot, regression results, and residual plots for these data.        
-Are the assumptions/conditions for regression and inference satisfied? Explain.

Accepted Answer

• Linearity condition: There is no obvio

Question 4

Consider the following to answer the question(s) below:
A sales manager was interested in determining if there is a relationship between college GPA and sales performance among salespeople hired within the last year. A sample of recently hired salespeople was selected and the number of units each sold last month was recorded. Relevant data appear in the table below.
   Below are the scatterplot, regression results, and residual plots for these data.        
-The confidence interval and prediction interval for the number of units sold per month when GPA = 3.00 are shown below. Interpret both intervals in this context.

Accepted Answer

We can be 95% confident that the number

Question 5

Consider the following to answer the question(s) below:
A study was recently performed by the Canada Revenue Agency to determine how much tip income waiters and waitresses would make based on the size of the bill at the table. A random sample of bills and resulting tips was collected. These data and regression results are as follows:
    
-In testing the null hypothesis H0: β1 = 0, the correct value of the test statistic is

Accepted Answer

A)  7.5634. 
B)  2.0202. 
C)  0.0281. 
D)  0.0001. 
E)  0.2128. 
A)  7.5634. 
B)  2.0202. 
C)  0.0281. 
D)  0.0001. 
E)  0.2128.

Question 6

Consider the following to answer the question(s) below:
A study was recently performed by the Canada Revenue Agency to determine how much tip income waiters and waitresses would make based on the size of the bill at the table. A random sample of bills and resulting tips was collected. These data and regression results are as follows:
    
-Based upon the regression equation   = -0.6684 + 0.2128x, what is the predicted value for tips if the total bill is $100?

Accepted Answer

A)  $20.61 
B)  $26.03 
C)  $15.55 
D)  $12.88 
E)  $21.28 
A)  $20.61 
B)  $26.03 
C)  $15.55 
D)  $12.88 
E)  $21.28

Question 7

Consider the following to answer the question(s) below:
A sales manager was interested in determining if there is a relationship between college GPA and sales performance among salespeople hired within the last year. A sample of recently hired salespeople was selected and the number of units each sold last month was recorded. Relevant data appear in the table below.
   Below are the scatterplot, regression results, and residual plots for these data.        
-Is there a significant relationship between sales performance (units sold per month) and college GPA (use α = 0.05)? Give the appropriate test statistic, associated P-value, and conclusion.

Accepted Answer

The test for regression slope results in

Question 8

Consider the following to answer the question(s) below:
A sales manager was interested in determining if there is a relationship between college GPA and sales performance among salespeople hired within the last year. A sample of recently hired salespeople was selected and the number of units each sold last month was recorded. Relevant data appear in the table below.
   Below are the scatterplot, regression results, and residual plots for these data.        
-The percentage of variability in sales performance (units sold per month) accounted for by college GPA is

Accepted Answer

A)  50.56%. 
B)  78.1%. 
C)  34.70%. 
D)  100%. 
E)  48.9%. 
A)  50.56%. 
B)  78.1%. 
C)  34.70%. 
D)  100%. 
E)  48.9%.

Question 9

Which of the following is true?

Accepted Answer

A)  When the correlation coefficient is significant, the slope coefficient will also be significant for a given level of α. 
B)  When the correlation coefficient is significant, the slope coefficient will never be significant for a given level of α. 
C)  The test statistics for the correlation coefficient and the slope coefficient are the same. 
D)  When the slope coefficient is significant, the correlation will not necessarily be significant for a given level of α. 
E)  The significance of the correlation and slope are unrelated. 
A)  When the correlation coefficient is significant, the slope coefficient will also be significant for a given level of α. 
B)  When the correlation coefficient is significant, the slope coefficient will never be significant for a given level of α. 
C)  The test statistics for the correlation coefficient and the slope coefficient are the same. 
D)  When the slope coefficient is significant, the correlation will not necessarily be significant for a given level of α. 
E)  The significance of the correlation and slope are unrelated.

Question 10

Consider the following to answer the question(s) below:
A sales manager was interested in determining if there is a relationship between college GPA and sales performance among salespeople hired within the last year. A sample of recently hired salespeople was selected and the number of units each sold last month was recorded. Relevant data appear in the table below.
   Below are the scatterplot, regression results, and residual plots for these data.        
-The residual standard deviation, which measures the spread of points around the estimated regression line, is

Accepted Answer

A)  3.256. 
B)  1.044. 
C)  1.63045. 
D)  34.70. 
E)  2.477. 
A)  3.256. 
B)  1.044. 
C)  1.63045. 
D)  34.70. 
E)  2.477.

Question 11

Consider the following to answer the question(s) below:
A sales manager was interested in determining if there is a relationship between college GPA and sales performance among salespeople hired within the last year. A sample of recently hired salespeople was selected and the number of units each sold last month was recorded. Relevant data appear in the table below.
   Below are the scatterplot, regression results, and residual plots for these data.        
-Write the null and alternative hypothesis.

Accepted Answer

H0: There is no association be

Question 12

Consider the following to answer the question(s) below:
An operations manager was interested in determining if there is a relationship between the amount of training received by production line workers and the time it takes for them to troubleshoot a process problem. A sample of recently trained line workers was selected. The number of hours of training time received and the time it took (in minutes) for them to troubleshoot their last process problem were captured. Relevant data appear in the table below.
   Below are the scatterplot, regression results, and residual plots for these data.          
-Write the null and alternative hypothesis.

Accepted Answer

H0: There is no association be

Which of the following is true?

Which of the following is true?

Data

Surveys and Sampling

Displaying and Describing Categorical Data

Displaying and Describing Quantitative Data

Scatterplots, Association, and Correlation

Introduction to Linear Regression

Randomness and Probability

Random Variables and Probability Distributions

Sampling Distributions

Confidence Intervals for Proportions

Testing Hypotheses About Proportions

Confidence Intervals and Hypothesis Tests for Means

Comparing Two Means

Design of Experiments and Analysis of Variance Anova

Inference for Counts: Chi-Square Tests

Nonparametric Methods

Understanding Regression Residuals

Multiple Regression

Building Multiple Regression Models

Time Series Analysis

Decision Making and Risk

Quality Control

Exploring and Collecting Data

Understanding Probability Distributions and Statistical Inference

Exploring Relationships Among Variables

Using Statistics for Decision Making

Filters

Exam 18: Inference for Regression

Which of the following is true?

Which of the following is true?

Data

Surveys and Sampling

Displaying and Describing Categorical Data

Displaying and Describing Quantitative Data

Scatterplots, Association, and Correlation

Introduction to Linear Regression

Randomness and Probability

Random Variables and Probability Distributions

Sampling Distributions

Confidence Intervals for Proportions

Testing Hypotheses About Proportions

Confidence Intervals and Hypothesis Tests for Means

Comparing Two Means

Design of Experiments and Analysis of Variance Anova

Inference for Counts: Chi-Square Tests

Nonparametric Methods

Understanding Regression Residuals

Multiple Regression

Building Multiple Regression Models

Time Series Analysis

Decision Making and Risk

Quality Control

Exploring and Collecting Data

Understanding Probability Distributions and Statistical Inference

Exploring Relationships Among Variables

Using Statistics for Decision Making

Filters