This document contains an exam for a statistics course. It includes multiple choice questions, true/false questions, and short answer/calculation questions covering topics like regression analysis, hypothesis testing, and ANOVA. The exam tests understanding of key concepts in statistical inference through various question types requiring calculations and interpretations.
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Exam spring 2016 eco 578.docx
1. Exam spring 2016 eco 578
Name:
_______________ ID: _______________Final ExamPart A: Multiple Choice
(1–11) Using the “eyeball” method, the regression line y ̂ = 2+2x has been fitted to the data
points (x = 2, y = 1), (x = 3, y = 8), and (x = 4, y = 7). The sum of the squared residuals will
be7b. 19 c. 34d. 8 A computer statistical package has included the following quantities in its
output: SST = 50, SSR = 35, and SSE = 15. How much of the variation in y is explained by the
regression equation?49% b. 70%c. 35%d. 15% In testing the significance of b_1, the null
hypothesis is generally thatβ = b_1 b. β ≠ 0c. β = 0d. β = r Testing whether the slope of the
population regression line could be zero is equivalent to testing whether the population
_____________ could be zero.standard error of estimatec. y-interceptprediction intervald.
coefficient of correlation A multiple regression equation includes 4 independent variables,
and the coefficient of multiple determination is 0.64. How much of the variation in y is
explained by the regression equation?80%b. 16%c. 32%d. 64% A multiple regression
analysis results in the following values for the sum-of-squares terms: SST = 50.0, SSR = 35.0,
and SSE = 15.0. The coefficient of multiple determination will be R^2= 0.35b. R^2= 0.30c.
R^2= 0.70 d. R^2= 0.50 In testing the overall significance of a multiple regression equation
in which there are three independent variables, the null hypothesis is H_(0 ): β_1= β_2=
β_3=0H_(0 ): β_1≠ β_2 and β_2 ≠β_3H_(0 ): β_1= β_2=β_3=1H_(0 ): β_1= β_2=β_3=α In a
multiple regression analysis involving 25 data points and 4 independent variables, the sum-
of-squares terms are calculated as SSR = 120, SSE = 80, and SST = 200. In testing the overall
significance of the regression equation, the calculated value of the test statistic will be F =
1.5c. F = 5.5F = 2.5d. F = 7.5 For a set of 15 data points, a computer statistical package has
found the multiple regression equation to be y ̂ = -23 + 20x_1+ 5x_2 + 25x_3 and has listed
the t-ratio for testing the significance of each partial regression coefficient. Using the 0.05
level in testing whether b_1= 20 differs significantly from zero, the critical t values will be t
= -1.960 and t= +1.960t = -2.132 and t = +2.132t = -2.201 and t = +2.201t = -1.796 and t =
+1.796 Computer analyses typically provide a p-Value for each partial regression
coefficient. In the case of b_1, this is the probability thatβ_1 = 0b_1 = β_1the absolute value
of b_1could be this large if β_1= 0the absolute value of b_1could be this large if β_1≥ 1In the
multiple regression equation, y ̂ = 20,000 + 0.05x_1+ 4500x_2 , y ̂ is the estimated
household income, x_1 is the amount of life insurance held by the head of the household,
and x_2 is a dummy variable (x_2 = 1 if the family owns mutual funds, 0 if it doesn’t). The
interpretation of b_2 = 4500 is thatowing mutual funds increases the estimated income by
2. $4500the average value of a mutual funds portfolio is $450045% of the persons in the
sample own mutual fundsthe sample size must have been at least n = 4500 Part B: True or
False (12-20) _______ 12. The usual objective of regression analysis is to predict estimate the
value of one variable when the value of another variable is known. _______ 13. Correlation
analysis is concerned with measuring the strength of the relationship between two
variables. _______ 14. In the least squares model, the explained sum of squares is always
smaller than the regression sum of squares. _______ 15. The sample correlation coefficient
and the sample slope will always have the same sign. _______ 16. An important relationship in
regression analysis is(Y_i-Y ̅ )=(Y ̂-Y ̅ )+(Y_i-Y ̂). _______ 17. If in a regression analysis the
explained sum of squares is 75 and the unexplained sum of square is 25, r2 = 0.33. _______
18. When small values of Y tend to be paired with small values of X, the relationship
between X and Y is said to be inverse. _______ 19. The probability that the test statistic will
fall in the critical region, given that H0 is true, represents the probability of making a type II
error. _______ 20. When we reject a true null hypothesis, we commit a Type I error. Part C:
Please fill in the blank and circle your decision or answer the following questions (21-
25). State whether you would reject or fail to reject the null hypothesis in each of the
following cases (two-tailed): Make a decision. P = 0.12 ; α=0.05DecisionReject / Fail to
reject P = 0.03 ; α=0.05DecisionReject / Fail to reject P = 0.001 ; α=0.01DecisionReject /
Fail to reject 22. State whether H_0 should be accepted or rejected for α=0.05, given the
following; F^*= computed F (fill in the blank and circle your decision) a) F^* = 2.34; df = 2
and 11Computed FCritical FDecision ________ ________Reject / Fail to reject b) F^* = 2.52; df =
4 and 20Computed FCritical FDecision ________ ________Reject / Fail to reject c) F^* = 4.29; df
= 3 and 24Computed FCritical FDecision ________ ________Reject / Fail to reject 23. Given the
following, complete the ANOVA table and make the correct inference. Using F-value to make
a
decision.SourceSSdfMSFTreatments_____23.24_____Error_____17_____ Total40.98_____ ANSW
ERa) What is the hypothesis being tested in this problem?b) In the above ANOVA table, is
the factor significant at the 5% level? c) What is the number of observations? 24. Given
the following, complete the ANOVA table and make the correct inference. Using F-value to
make a
decision.SourceSSdfMSFTreatments____5205.5____Error637________ Total____25 ANSWERa)
What is the hypothesis being tested in this problem?b) In the above ANOVA table, is the
factor significant at the 5% level? c) What is the number of observations? 25. Given the
following, complete the ANOVA table and make the correct inference. Using F-value to make
a decision.SourceSSdfMSFTreatments____3________Error88.8________ Total43519 ANSWERa)
What is the hypothesis being tested in this problem?b) In the above ANOVA table, is the
factor significant at the 5% level? c) What is the number of observations? Part D: Must
show all your work step by step in order to receive the full credit; Excel is not allowed. (26-
38) Consider the following hypothesis test. Ho: µ = 17 Ha: µ ≠ 17 A sample of 25
gives a sample mean of 14.2 and sample variance of 25. a)At 5% should the null be
rejected?b) Compute the value of the test statistic c)What is the p-value? d) What is your
conclusion? Consider the following hypothesis testHo: µ ≥ 10Ha: µ < 10A sample of 50
provides a sample mean of 9.46 and sample variance of 4.a)At 5% should the null be
3. rejected?b) Compute the value of the test statistic c)What is the p-value? d) What is your
conclusion? Use problem 13 on page 9-20 to answer the following questions. (info on
last page) What is the sample mean What is the sample standard deviation Use Z or T
test? And why? What is your hypothesis test At α = 0.05, what is the rejection rule?
Compute the value of the test statistic. What is the p-value? What is your conclusion? Use
problem 7 on page 9-36 to answer to following questions. (info on last page of
document) a)At 5% should the null be rejected?b) Compute the value of the test
statistic c)What is the p-value? d) What is your conclusion? 30. For n=6 data point,
the following quantities have been calculated.∑xy = 400∑x = 40∑y = 76∑x2 = 346∑y2 =
1,160a)Find b_1 b)Find b_0 c)Write the equation d)Find (R^2 ) ̅ e)Find
SST f)Find S_e g) Construct the 95% confidence interval for the mean of y when x =
7 h) Construct the 95% confidence interval for the individual value of y when x = 7Please
fill in the computer printout and answer the following questions. Given that
α=0.05 SUMMARY OUTPUTRegression StatisticsMultiple R0.9037R Square______Adjusted R
Square______Standard Error______Observations5ANOVA dfSSMSFSignificance
FRegression14.9____________0.03535Residual31.1______Total____________ CoefficientsStandard
Errort StatP-valueLower95%Upper 95%Lower 95.0%Upper 95.0%Intercept-0.1______-
0.157460.88488-2.121121.92112-2.121121.92112X1
0.7______3.655630.035350.090611.30939____________ a) What percent of the variation is
explained by the regression equation? b) What is the standard error of regression? c)
What is the critical value of the F-statistic? d) What sample size is used in the print
out? The following regression equation was obtained using the five independent variables.
Given that α=0.05 a) What percent of the variation is explained by the regression
equation b) What is the standard error of regression? c) Write the estimated
equation. d) What is the critical value of the F-statistic?e) What sample size is used in the
print out? f) What is the variance of the slope coefficient of income?g) Assuming that you
are using a two-tailed test make a decision using the computed P-value. 33. Use problem
5 on page 15-9 to answer the following questions. (a-d) (info on last page) What is you
hypothesis testing What is your χ^2? c) Is the χ^2 value significant at 5% level
of significance? d) Write the conclusion for this question. 34. Eighty Frat Rats were
blindfolded and given a taste test on different brands of beer. The table below shows the
beer brands preferred. Test to see if the data fits a uniform distribution (i.e., what would
happen if the Frat Rats can’t tell one beer from another). Use 5% level of significance. Beer
BrandNumber of Preferring that BrandBud Light32Coors Light18Molton Golden14Miller
Light16What is you hypothesis testing What is your χ^2? c) Is the χ^2 value
significant at 5% level of significance? d) Write the conclusion for this question. 35. Use
the computer printout below to answer the following questions.CoefficientsStd. Errort-
StatP-valueIntercept729.8665169.257514.31216590.0010099Price-10.8873.4952397-
3.11480780.0089406Advertising0.04650.01762282.63862970.0216284 ANOVAdfSSMSFSi
gnificance
FRegression212442.86221.437.561279940.00000683Residual121987.6165.63333Total14
14430.4Se =12.86986 R-sq = 0.862263 R-sq(adj) = 0.8393068α=5%a) Write
and interpret the multiple regression equation b) Does the model with Price and
4. Advertising contribute to the prediction of Y? c) Which independent variable appears to be
the best predictor of sales? Explain. d) What is the number of observations used in this
study? e)Find SST Assuming that the coefficient on Advertising has Ha: B1 > 0, what’s
statistical decision ? f) What is the standard error of estimate? Can you use this statistic
to assess the model’s fit? If so, how? g) What is the coefficient of determination, and what
does it tell you about the regression model? h) What is the coefficient of determination,
adjusted for degrees of freedom? What do this statistic and the statistic referr to in part (g)
tell you about how well this model fits that data. i) Test the overall utility of the model.
What does the p-value of the test statistic tell you? 36. Explain why a 95% confidence
interval estimate for the mean value of y at a particular x is narrower than a 95%
confidence interval for an individual y value at the same value of x. 37. If R^2=0.95,
n=11, and ∑▒〖〖(Y-Y ̅)〗^2=100,〗 what is S_e^2? 38. You are given the following
information from fitting a multiple regression with three variables to 30 sample data
points:b_1=1.3b_2=10.0b_3=25.2S_(b_1 )=0.3S_(b_2 )=2.0S_(b_3 )=15.0Test the following
hypotheses, Use α=0.05a) β_1=0 b) β_2=0 a) β_3=0