Exam 17: Regression Models With Dummy Variables

A model formulated as y = β₀ + β₁x + ε = P(y = 1) + ε is called a(n) ________ probability model.

According to the Center for Disease Control and Prevention, life expectancy at age 65 in America is about 18.7 years. Medical researchers have argued that while excessive drinking is detrimental to health, drinking a little alcohol every day, especially wine, may be associated with the increase in life expectancy. Others have also linked longevity with income and gender. The data relating to the length of life after 65 (Life) were collected. Data were collected related to the length of life after 65 (Life) including the average income (in $1,000s) (Income), the average number of alcoholic drinks consumed per day (Drinks), and a dummy variable Woman which is 1 when the individual is a woman and 0 otherwise. The following model was created: Life = β₀ + β₁Income + β₂Drinks + β₃Woman + ε. Output corresponding to this model is shown below. Which of the following is the difference in life expectancy for 65-year-old women consuming two drinks per day and men consuming one drink per day, and having the same income?

A researcher wants to examine how the remaining balance on $100,000 loans taken 10 to 20 years ago depends on whether the loan was a prime or subprime loan. He collected a sample of 25 prime loans and 25 subprime loans and recorded the data in the following variables: Balance = the remaining amount of loan to be paid off (in $), Time = the time elapsed from taking the loan, Prime = a dummy variable assuming 1 for prime loans, and 0 for subprime loans. The regression results obtained for the models: Model A: Balance = β₀ + β₁Prime + ε Model B: Balance = β₀ + β₁Time + β₂Prime + β₃Time × Prime + ε Model C: Balance = β₀ + β₁Prime + β₂Time × Prime + ε, Are summarized in the following table. Note: The values of relevant test statistics are shown in parentheses below the estimated coefficients. Suppose that at a 10% significance level, you do not reject the null hypothesis, H₀: β₁ = 0, when testing the individual significance of Time in Model B. Would you delete Time from Model B?

For the model y = β₀ + β₁x + β₂d + β₃xd + ε, the dummy variable d causes only a shift in intercept.

Like any other university, Seton Hall University uses SAT scores and high school GPAs as primary criteria for admission. Data for 30 students who had recently applied to Seton Hall were collected including admission (1 for admission and 0 otherwise), SAT score, and GPA. Output for the model is shows below. Which of the following is the estimated logistic model?

According to the Center for Disease Control and Prevention, life expectancy at age 65 in America is about 18.7 years. Medical researchers have argued that while excessive drinking is detrimental to health, drinking a little alcohol every day, especially wine, may be associated with the increase in life expectancy. Others have also linked longevity with income and gender. The data relating to the length of life after 65 (Life) were collected. Data were collected related to the length of life after 65 (Life) including the average income (in $1,000s) (Income), the average number of alcoholic drinks consumed per day (Drinks), and a dummy variable Woman which is 1 when the individual is a woman and 0 otherwise. . The following model was created: Life = β₀ + β₁Income + β₂Drinks + β₃Woman + ε. Output corresponding to this model is shown below. Which of the following is the predicted life expectancy for a 65-year-old woman with an income of $60,000 and a consumption of one drink per day?

To examine the differences between salaries of male and female middle managers of a large bank, 90 individuals were randomly selected, and two models were created with the following variables considered: Salary = the monthly salary (excluding fringe benefits and bonuses), Educ = the number of years of education, Exper = the number of months of experience, Train = the number of weeks of training, Gender = the gender of an individual; 1 for males, and 0 for females. Excel partial outputs corresponding to these models are available and shown below. Model A: Salary = β₀ + β₁Educ + β₂Exper + β₃Train + β₄Gender + ε Model B: Salary = β₀ + β₁Educ + β₂Exper + β₃Gender + ε Using Model B, what is the regression equation for males?

A bank manager is interested in assigning a rating to the holders of credit cards issued by her bank. The rating is based on the probability of defaulting on credit cards and is as follows. To estimate this probability, she decided to use the logit model, P = , where y = a binary response variable which is 1 if the credit card is in default and 0 otherwise x₁ = the ratio of the credit card balance to the credit card limit (in %) x₂ = the ratio of the total debt to the annual income (in %) The following output is obtained. Note: The p-values of the corresponding tests are shown in parentheses below the estimated coefficients. What are the conclusions of the tests of individual significance for the balance ratio and the debt ratio at the 1% level?

A realtor wants to predict and compare the prices of homes in three neighboring locations. She considers the following linear models: Model A: Price = β₀ + β₁ Size + β₂ Age + ε Model B: Price = β₀ + β₁ Size + β₃ Loc1 + β₄ Loc2 + ε Model C: Price = β₀ + β₁ Size + β₂ Age + β₃ Loc1 + β₄ Loc2 + ε where, Price = the price of a home (in $1,000s) Size = the square footage (in sq. feet) Loc1 = a dummy variable taking on 1 for Location 1, and 0 otherwise Loc2 = a dummy variable taking on 1 for Location 2, and 0 otherwise After collecting data on 52 sales and applying regression, her findings were summarized in the following table. Note: The values of relevant test statistics are shown in parentheses below the estimated coefficients. Which of these three models would you choose to make the predictions of the home prices?

A researcher wants to examine how the remaining balance on $100,000 loans taken 10 to 20 years ago depends on whether the loan was a prime or subprime loan. He collected a sample of 25 prime loans and 25 subprime loans and recorded the data in the following variables: Balance = the remaining amount of loan to be paid off (in $), Time = the time elapsed from taking the loan, Prime = a dummy variable assuming 1 for prime loans, and 0 for subprime loans. The regression results obtained for the models: Model A: Balance = β₀ + β₁Prime + ε Model B: Balance = β₀ + β₁Time + β₂Prime + β₃Time × Prime + ε Model C: Balance = β₀ + β₁Prime + β₂Time × Prime + ε, Are summarized in the following table. Note: The values of relevant test statistics are shown in parentheses below the estimated coefficients. Using Model B, what is the value of the test statistic for testing the joint significance of the variable Time and the interaction variable Time × Prime?

Variables employed in a regression model can be quantitative or qualitative.

An over-the-counter drug manufacturer wants to examine the effectiveness of a new drug in curing an illness most commonly found in older patients. Thirteen patients are given the new drug and 13 patients are given the old drug. To avoid bias in the experiment, they are not told which drug is given to them. To check how the effectiveness depends on the age of patients, the following data have been collected. The variables are Effectiveness = the response variable measured on a scale from 0 to 100, Age = the age of a patient (in years), Drug = a dummy variable that is 1 for the new drug and 0 for the old drug. The regression model, Effectiveness = β₀ + β₁Age + β₂Drug + β₃Age × Drug, , is estimated and the following results are obtained. Which of the following is the predicted effectiveness of the old drug for a 62-year-old patient?

An over-the-counter drug manufacturer wants to examine the effectiveness of a new drug in curing an illness most commonly found in older patients. Thirteen patients are given the new drug and 13 patients are given the old drug. To avoid bias in the experiment, they are not told which drug is given to them. To check how the effectiveness depends on the age of patients, the following data have been collected. The variables are Effectiveness = the response variable measured on a scale from 0 to 100, Age = the age of a patient (in years), Drug = a dummy variable that is 1 for the new drug and 0 for the old drug. The regression model, Effectiveness = β₀ + β₁Age + β₂Drug + β₃Age × Drug, , is estimated and the following results are obtained. Which of the following is true?

For the linear probability model y = β₀ + β₁x + ε, the predicted value of y is always constrained to be ________.

An over-the-counter drug manufacturer wants to examine the effectiveness of a new drug in curing an illness most commonly found in older patients. Thirteen patients are given the new drug and 13 patients are given the old drug. To avoid bias in the experiment, they are not told which drug is given to them. To check how the effectiveness depends on the age of patients, the following data have been collected. The variables are Effectiveness = the response variable measured on a scale from 0 to 100, Age = the age of a patient (in years), Drug = a dummy variable that is 1 for the new drug and 0 for the old drug, The regression model, Effectiveness = β₀ + β₁Age + β₂Drug + β₃Age × Drug,is estimated and the following results are obtained. Which of the following is the estimated regression model for the old drug?

In the model y = β₀ + β₁x + β₂d + β₃xd + ε, when d changes from 0 to 1 how does the intercept of the corresponding lines change?

Consider the regression equation = b₀ + b₁x + b₂d with a dummy variable d. If d changes from 0 to 1, the intercept changes by:

Which of the following variables is not qualitative?

In the regression equation = b₀ + b₁x + b₂d, a dummy variable d affects the slope of the line.

A researcher wants to examine how the remaining balance on $100,000 loans taken 10 to 20 years ago depends on whether the loan was a prime or subprime loan. He collected a sample of 25 prime loans and 25 subprime loans and recorded the data in the following variables: Balance = the remaining amount of loan to be paid off (in $), Time = the time elapsed from taking the loan, Prime = a dummy variable assuming 1 for prime loans, and 0 for subprime loans. The regression results obtained for the models: Model A: Balance = β₀ + β₁Prime + ε Model B: Balance = β₀ + β₁Time + β₂Prime + β₃Time × Prime + ε Model C: Balance = β₀ + β₁Prime + β₂Time × Prime + ε, Are summarized in the following table. Note: The values of relevant test statistics are shown in parentheses below the estimated coefficients. Using Model B, which of the following is the alternative hypothesis for testing the significance of Time?