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Statistics for Management and Economics
Exam 17: Multiple Regression
Path 4
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Question 1
True/False
In multiple regression analysis,the adjusted coefficient of determination is adjusted for the number of independent variables and the sample size.
Question 2
True/False
In a multiple regression analysis involving 50 observations and 5 independent variables,the total variation in y is 475 and SSE = 71.25.Then,the coefficient of determination is 0.85.
Question 3
Essay
Discuss two indicators that can be found in an analysis that suggest multicollinearity is present.
Question 4
Essay
Life Expectancy An actuary wanted to develop a model to predict how long individuals will live.After consulting a number of physicians,she collected the age at death (y),the average number of hours of exercise per week (x
1
),the cholesterol level (x
2
),and the number of points that the individual's blood pressure exceeded the recommended value (x
3
).A random sample of 40 individuals was selected.The computer output of the multiple regression model is shown below. THE REGRESSION EQUATION IS y = 55.8 + 1.79x
1
− 0.021x
2
− 0.061x
3
S = 9.47 R−Sq = 22.5% ANALYSIS OF VARIANCE
-{Life Expectancy Narrative} Is there enough evidence at the 5% significance level to infer that the model is useful in predicting length of life?
Question 5
Multiple Choice
In a multiple regression analysis involving 40 observations and 5 independent variables,the following statistics are given: Total variation in y = 350 and SSE = 50.Then,the coefficient of determination is:
Question 6
Short Answer
A multiple regression model has the form
.The coefficient b
1
is interpreted as the change in the average value of y per unit change in ________ holding ________ constant.
Question 7
Essay
Life Expectancy An actuary wanted to develop a model to predict how long individuals will live.After consulting a number of physicians,she collected the age at death (y),the average number of hours of exercise per week (x
1
),the cholesterol level (x
2
),and the number of points that the individual's blood pressure exceeded the recommended value (x
3
).A random sample of 40 individuals was selected.The computer output of the multiple regression model is shown below. THE REGRESSION EQUATION IS y = 55.8 + 1.79x
1
− 0.021x
2
− 0.061x
3
S = 9.47 R−Sq = 22.5% ANALYSIS OF VARIANCE
-{Life Expectancy Narrative} Is there enough evidence at the 1% significance level to infer that the average number of hours of exercise per week and the age at death are linearly related?
Question 8
Short Answer
Multiple regression has four requirements for the error variable.One is that the probability distribution of the error variable is ____________________.
Question 9
True/False
A small value of F indicates that most of the variation in y is explained by the regression equation and that the model is useful.
Question 10
Multiple Choice
The coefficient of determination ranges from:
Question 11
Short Answer
Real Estate Builder A real estate builder wishes to determine how house size is influenced by family income,family size,and education of the head of household.House size is measured in hundreds of square feet,income is measured in thousands of dollars,and education is measured in years.A partial computer output is shown below. SUMMARY OUTPUT Regression Statistics Multiple R 0.865 R Square 0.748 Adjusted R Square 0.726 Standard Error 5.195 Observations 50 ANOVA
-{Real Estate Builder Narrative} Which of the following values for the level of significance is the smallest for which all explanatory variables are significant individually: α = .01,.05,.10,or .15?
Question 12
True/False
If the value of the Durbin-Watson test statistic,d,satisfies the inequality d > 4 −d
L
,we conclude that positive first-order autocorrelation exists.
Question 13
True/False
In reference to the equation
,the value 0.12 is the average change in y per unit change in x
1
,when x
2
is held constant.
Question 14
True/False
If the value of the Durbin-Watson test statistic,d,satisfies the inequalities d < d
L
or d > 4 −d
L
,where d
L
and d
U
are the critical values of d,we conclude that autocorrelation exists.
Question 15
True/False
In testing the significance of a multiple regression model with three independent variables,the null hypothesis is
.
Question 16
Short Answer
Some of the requirements for the error variable in a multiple regression model are that the probability distribution is ____________________ with a mean of ____________________.
Question 17
Multiple Choice
If the Durbin-Watson statistic has a value close to 4,which assumption is violated?
Question 18
True/False
A multiple regression model is assessed to be good if the error sum of squares SSE and the standard error of estimate sε are both small,the coefficient of determination R
2
is close to 1,and the value of the test statistic F is large.
Question 19
Essay
Consider the following statistics of a multiple regression model: Total variation in y = 1000,SSE = 300,n = 50,and k = 4. a.Determine the standard error of estimate. b.Determine the coefficient of determination. c.Determine the F-statistic.