Exam 15: Model Building and Model Diagnostics

A multiple regression model was applied to a data set with 8 time ordered observations.The residuals for these observations are given below. Calculate the Durbin-Watson statistic (d).

Based on 30 time ordered observations from a multiple regression model with 2 independent variables,we have determined the Durbin-Watson statistic,d = 2.71.At $\alpha$ = .05,test to determine if there is any evidence of negative autocorrelation? State your conclusions.

A county has four major hospitals: 1)Regional Memorial;2)General;3)Charity;and 4)City.A multiple regression model is used to compare the time spent in the hospital after a heart by-pass surgery among the four hospitals.The response (dependent)variable is the amount of time spent in the hospital (in days).The variables used to predict the time spent in the hospital include the patient's age,cholesterol level (in mlg. ),blood pressure,as well as variables indicating the hospital in which the surgery was performed.Determine the total number of independent variables in the multiple regression model.Indicate how many of these are quantitative variables and how many are indicator (dummy)variables.

_________ regression method is used when the response variable is a qualitative or a categorical variable.

The _____________ statistic is used to test for autocorrelation among the residuals.

In a multiple regression model with 4 independent variables and 25 observations,an observation's actual y value is 128.2,and the predicted value of the dependent variable based on the multiple regression equation is equal to 114.7.The computer output also shows that MSE is equal to 144 and the leverage value is 0.19.Calculate the adjusted R² where R² = .716,the number of observations is 20,and the number of independent variables is 2.

Adding any independent variable to a regression model will increase

One way to identify outliers with respect to their x values is to calculate their leverage values.

The _____ procedure works the same way as the stepwise regression procedure except that once an independent variable is eliminated from the model,it is never returned to the model.

In a multiple regression analysis,the current model has three independent variables.The analyst decides to add another (fourth)independent variable while retaining the other three independent variables.As a result of this addition,the value of explained variation will ____________ decrease.

A multiple linear regression analysis involving 45 observations resulted in the following least squares prediction equation: .

Below is a partial multiple regression computer output based on a quadratic regression model. Calculate R².

The variance inflation factor measures the relationship between the dependent variable and the rest of the independent variables in the regression model.

A multiple linear regression analysis involving 45 observations resulted in the following least squares prediction equation: .

A(n)_____ observation is an observation that causes the least squares point estimates to be substantially different from what they would be if the observation were removed from the data.

In comparing regression models,the regression model with the largest R² will also have the smallest standard error(s).

If the Durbin-Watson statistic is greater than (4 - d_L),then it is concluded that

All of the following are desirable outcomes for a multiple regression model except

If we increase the number of independent variables in a multiple regression model,the F statistic will always increase.

When there are indications of autocorrelation,first an investigation should be conducted to determine whether one or more independent variables that might explain the autocorrelation have been omitted from the model.