Exam 4: Regression Models

The regression line minimizes the sum of the squared errors.

The MBA program surveyed the catastrophe that was his fall 2017 intake.His 257 admitted students had performed miserably and he needed to determine why.He built a regression model to predict their overall class average after their first semester based on these factors that weighed heavily in their admission process: undergraduate GPA, GMAT score, years of professional employment, shoe size, TOEFL score, and 40 yard dash.How many degrees of freedom should the F test denominator have?

The primary difference between r² and the adjusted r² is that

A dummy variable can be assigned up to three values.

An electronics company is looking to develop a regression model to predict the number of units sold for a special running watch.Data is provided below: Use model building to determine the best prediction equation for Sales, based on highest adjusted r².

Transformations may be used when nonlinear relationships exist between variables.

What can be said about a correlation coefficient of -1?

Table 4.1 SUMMARY OUTPUT ANOVA -Consider the output shown in Table 4.1.Which of the predictors has the greatest impact on the dependent variable?

Which of the following conditions can be detected from residual analysis?

Which of these statements is best?

The problem of nonconstant error variance is detected in residual analysis by which of the following?

A reference to the criterion used to select the regression line, to minimize the squared distances between the estimated straight line and the observed values is called

A healthcare executive is using regression to predict total revenues.She is deciding whether or not to include both patient length of stay and insurance type in her model.Her first regression model only included patient length of stay.The resulting r² was .83, with an adjusted r² of .82 and her level of significance was .003.In the second model, she included both patient length of stay and insurance type.The r² was .84 and the adjusted r² was .80 for the second model and the level of significance did not change.Which of the following statements is true?

In regression, there is random error that can be predicted.

Explain the purposes of regression models.

If computing a causal linear regression model of Y = a + bX and the resultant r² is very near zero, then one would be able to conclude that

Which of the following statements is false concerning the hypothesis testing procedure for a regression model?

Bob White is conducting research on monthly expenses for medical care, including over the counter medicine.His dependent variable is monthly expenses for medical care while his independent variables are number of family members and insurance type (government funded, private insurance and other).He has coded insurance type as the following: X2 = 1 if government funded, X3 = 1 if private insurance Below is his Excel output. ANOVA (a)What is the prediction equation? (b)Based on the significance F-test, is this model a good prediction equation? (c)What percent of the variation in medical expenses is explained by the independent variables? (d)Based on his model, what are the predicted monthly expenses for a family of four with private insurance? (e)Based on his model, what are the predicted monthly expenses for a family of two with government funded insurance? (f)Based on his model, what are the predicted monthly expenses for a family of five with no insurance?

Suppose that you believe that a cubic relationship exists between the independent variable (of time)and the dependent variable Y.Which of the following would represent a valid linear regression model?

The correlation coefficient has values between −1 and +1.