Exam 5: Hypothesis Testing in Linear Regression Analysis
When using the p-value method for hypothesis testing,if the calculated p-value is smaller than the chosen significance level,then you should
A
Why are each of the individual simple linear regression model assumptions important? Explain.
Assumption 1:If the model is not correctly specified then the estimates based on it will not be meaningful or true.
Assumption 2:If the data is not collected through random sampling then a model that is specified conditional on the observations not being related to each other then the estimated coefficients will be wrong.
Assumption 3:If the independent variable does not vary then
is not defined and therefore an estimate cannot be derived.
Assumption 4:If the average value of the error term is not equal to zero then the estimates on average will be wrong on average.
Assumption 5:If the error term is related to the independent variables,then if the independent variable increases by one unit then the error term will increase as well,therefore not allowing for a measurement of how the independent variable affects the dependent variable holding other factors constant (because the error term changed as well).
Assumption 6:If the variance of the error term is not constant then OLS,that treat all observations the same,is not the most preferred method to estimate the regression model.
A counselor working with teenagers is interested in the relationship between anxiety and depression.The counselor administers a depression and anxiety test to each teenager.The scores obtained from the administration of the two inventories are given below. Anxiety Depression 22 16 12 8 68 33 10 6 5 5 53 24 44 18 37 17 0 2 21 14 64 31 33 17 55 30 18 13 3 3 4 4 11 7 13 9 7 5
The summary statistics are Anxiety Depression Sample mean 25.2632 13.7895 Standard deviation 21.9895 9.8464
If an individual had an anxiety score of 40,what is a 95% confidence interval for the mean predicted value?
This means if a person scores 40 on the anxiety test they are predicted to score 20.27 on the depression test.
critical value = 2.11
standard error = 0.5298
95% confidence interval for the mean value is (19.1531,21.2889).
The t-statistic for the individual significance of the estimated slope coefficient Is
Figure:
Suppose you regress U.S.annual real GDP ($ billions)on U.S.annual real defense expenditures ($ millions)and that you get the following results. SUMMARY OUTPUT
Regvessiait Statistics Muatiple R. 0.523337059 R Sqare 0.273881677 Adjusted R Square 0.263508558 Standard Error 3201.551247 Obsenvations 72
ANOVA of SS MS F Siguffecance F Regressice 1 270629128.2 270629128.2 26.4030211 2.39636-06 Residual 70 717495127 10249930.39 Total 71 988124255.3
Coeffieients Staudard Errar t Stat P-value Lower 95\% Upper 95\%6 linercept 1273.293919 979.7967762 1.299548998 0.198019186 -680.8491085 3227.436946 Real Defense Expesdtures (milions) 0.013659042 0.002658235 5.138387013 2.39636-06 0.008357359 0.018960725
-Based on the Excel output in Figure 5.1,you should conclude that
What is the intuition behind the critical-value method of hypothesis testing? Explain.
The logic behind the F-test for the overall significance of the estimated sample regression function is that if the estimated sample regression function explains a significant amount of the variation in the dependent variable,then
The logic behind the t-test for the individual significance of the estimated slope coefficient
Is that if the estimated slope coefficient is likely to be different from 0,then
What is the intuition behind the confidence interval method of hypothesis testing? Explain.
The p-value method for hypothesis testing relies on the fact that
Figure
Suppose you regress obesity rates for the 50 states and the District of Columbia on the percentage of adults who have earned a Bachelor's degree and that you get the following results. SUMMARY OUTPUT
Regression Staristies Multple R. 0.755633848 R. Square 0.570982512 Adjasted R. Square 0.562227053 Standard Erroe 2.233627219 Observations 51
df SS MS F Significance F Regression 1 325,3608375 325.3608375 65.21445826 1.46476-10 Residual 49 244.465437 4.989090551 Total 50 569.8262745
Coefficients Standard Ewor t Stat P-value Lower 95\%6 Ueper 9596 Intercept 40.59256588 1.597069735 25.41690259 7.09161-30 37.38313415 43.80199761 Percent Aduhs with Bachelor's Deryee -0.465887223 0.057691105 -8.075546932 1.46476-10 -0.581821836 -0.34995261
-Based on the Excel output in Figure 5.2,you should conclude that the estimated sample regression function is
What is the intuition behind the p-value method of hypothesis testing? Explain.
Figure:
Suppose you regress U.S.annual real GDP ($ billions)on U.S.annual real defense expenditures ($ millions)and that you get the following results. SUMMARY OUTPUT
Regvessiait Statistics Muatiple R. 0.523337059 R Sqare 0.273881677 Adjusted R Square 0.263508558 Standard Error 3201.551247 Obsenvations 72
ANOVA of SS MS F Siguffecance F Regressice 1 270629128.2 270629128.2 26.4030211 2.39636-06 Residual 70 717495127 10249930.39 Total 71 988124255.3
Coeffieients Staudard Errar t Stat P-value Lower 95\% Upper 95\%6 linercept 1273.293919 979.7967762 1.299548998 0.198019186 -680.8491085 3227.436946 Real Defense Expesdtures (milions) 0.013659042 0.002658235 5.138387013 2.39636-06 0.008357359 0.018960725
-Based on the Excel output in Figure 5.1,you should conclude that the estimated sample regression function is
When using the critical value method for hypothesis testing,if the value of the test statistic is less than the critical value,then you should
If we find that it is unlikely to observe the sample statistic that is actually observed if the null hypothesis is true,then we should
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