Q1: This requires paying for the online cost. The cost is $249. Check the appendix; Q2: a)Consider a portfolio that holds 60% of its capital in X and 40% in Y. What is the distribution of the portfolio annual return? Solution The annual return of a portfolio is obtained based on the weight attached to the different stocks under investigation. The following formula is applied to compute the annualized return; Portfolioannualrturn=(wx∗μx)+(wy∗μy) Where, wx=weightgiven¿stockx μx=averagereturnsforstockx wy=weightgiven¿stocky μy=averagereturnsforstocky From the information given, we have; wx=60%=0.6;μx=0.10;wy=40%=0.6;μx=0.17
PortfolioAnnualReturn=0.6∗0.10+0.4∗0.17=0.128 b)Supposed that there are 21 observations of variable X with the mean of 13 and the sample standard deviation of 7. What is the probability of obtaining at least this result if the true average is 10? Solution P(x=13) Z=X−μ σ/√n=13−10 7/√21=1.964 P(13−10 7/√21)=P(Z=1.964)=0.0495 c)Supposed that there are 26 observations of variable Y with the mean of 16 and the sample standard deviation of 3. Construct the 95% and 90% confidence intervals for the population mean. Solution For 95% confidence interval We first obtain the standard error; S.E=σ √n=3 √26=0.588348 Zα/2=1.96 μ=16 C.I:μ±Zα/2SE 16±1.96∗0.588348 16±1.1532
Lower limit:16−1.1532=14.8468 Upper limit:16+1.1532=17.1532 From the above results of the confidence intervals computations, we are therefore 95% confident that the true mean is between 14.8468 and 17.1532. For 90% confidence interval We first obtain the standard error; S.E=σ √n=3 √26=0.588348 Zα/2=1.645 μ=16 C.I:μ±Zα/2SE 16±1.645∗0.588348 16±0.9678 Lower limit:16−0.9678=15.0322 Upper limit:16+0.9678=16.9678 From the above results of the confidence intervals computations, we are therefore 90% confident that the true mean is between 15.0322 and 16.9678. Q3: a)Compute 90% confidence intervals for the intercept (α) and the slope of the regression (β) Solution Coefficients Standard ErrortStatP-value Lower 95% Upper 95% Lower 90.0% Upper 90.0% Intercept43.62099.3630.4390.662-154.554241.793-122.011209.250
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FTSE0.0870.0155.7620.0000.0570.1170.0620.112 The 90% confidenceintervals for the intercept (α) is between -122.011 and 209.250. The 90% confidenceintervals for the slope of the regression (β) is between 0.062 and 0.112. b)Test the null hypothesisH0:β=0versus the alternativeH1:β≠0. Comment on the results of the test. Solution tβ=β SE(β)=0.087 0.015=5.762 The p-value is 0.000 (a value less than 5% level significance), we therefore reject the null hypothesis and conclude that the slope of the regression (β) is significantly different from zero(Hinkelmann & Kempthorne, 2008). c)Test the null hypothesisH0:β≤1versus the alternativeH1:β>1. Comment on the results of the test. Solution tβ=β−1 SE(β)=0.087−1 0.015=−60.867 Using the critical t value and the computed t –value we can conclude the null hypothesis is not rejected hencethe slope of the regression (β) is not significantly different from one (Tabachnick & Fidell, 2007). d)Test the significance of the slope using the F test Solution
ANOVA dfSSMSF Significanc eF Regressio n1158204.1158204.133.203092.05E-07 Residual70333531.84764.739 Total71491735.8 As can be seen from the above table, the p-value for the F-test is 0.000 (a value less than 5% level of significance), we therefore reject the null hypothesis and conclude that using the F-test, the slope is still significant in the model(Rubin & Little, 2012). e)Check your results with SPSS. Solution The SPSS results are presented below; Model Summary ModelRR SquareAdjusted R Square Std. Error of the Estimate 1.567a.322.31269.02709 a. Predictors: (Constant), FTSE ANOVAa ModelSum of SquaresdfMean SquareFSig. 1 Regression158204.0861158204.08633.203.000b Residual333531.761704764.739 Total491735.84771 a. Dependent Variable: HSBA.L b. Predictors: (Constant), FTSE Coefficientsa
ModelUnstandardized CoefficientsStandardized Coefficients tSig. BStd. ErrorBeta 1(Constant)43.62099.363.439.662 FTSE.087.015.5675.762.000 a. Dependent Variable: HSBA.L As can be seen from the above tables, it is evident that the same results are obtained by using SPSS(Gigerenzer, 2004). Q4: a)Run the regression:[HSBCt−rf,t]=β0+β1[FTSE100t−rf,t]+β2HMLt+β3SMBt+εtand interpret the regression results. Solution SUMMARYOUTPUT RegressionStatistics MultipleR0.570993 RSquare0.326032 AdjustedRSquare0.296299 StandardError69.81214 Observations72 ANOVA dfSSMSF Significance F Regression3160321.953440.6210.965025.83E-06 Residual683314144873.735 Total71491735.8 Coefficient s Standard ErrortStatP-value Lower 95% Upper 95% Intercep34.905101.3590.3440.732-167.355237.164
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t FTSE0.0880.0155.7350.0000.0580.119 SMB-0.1323.805-0.0350.972-7.7247.461 HML2.5143.8340.6560.514-5.13810.165 As can be seen from the above table, the p-value for the F-test is 0.000 (a value less than 5% level of significance), we therefore reject the null hypothesis and conclude that the model is fit and appropriate to estimate the dependent variable. b)Report the R2from this regression and compare that with the R2 in problem 3. What do you conclude? Solution R2refers to the coefficient of determination. The value helps determine the proportion of variation explained by the independent (explanatory) variables in the model(Imdadullah, 2008).The value of R-Squared is 0.3260; this implies that 32.6% of the variation in the dependent variable (HSBCt), is explained by the three independent variables in the model. c)Test the null hypothesis:H0:β1=β2=β3=0against the alternative:H1:β1≠0and/orβ2≠0 and/orβ3≠0. What do you conclude? Solution The p-value for FTSE is 0.000 (a value less than 5% level significance), we therefore rejectthenullhypothesisandconcludethattheslopeoftheregression(β1)is significantly different from zero.
The p-value for SMB is0.972(a value greater than 5% level significance), we therefore fail to reject the null hypothesis and conclude that the slope of the regression (β2) is not significantly different from zero. The p-value for HML is0.514(a value greater than 5% level significance), we therefore fail to reject the null hypothesis and conclude that the slope of the regression (β3) is not significantly different from zero. d)Test the null hypothesis:H0:β1=1andβ3=0against the alternativeH1:β1≠1and/or β3≠0. What do you conclude? Solution The p-value for FTSE is 0.000 (a value less than 5% level significance), we therefore rejectthenullhypothesisandconcludethattheslopeoftheregression(β1)is significantly different from zero. The p-value for SMB is0.972(a value greater than 5% level significance), we therefore fail to reject the null hypothesis and conclude that the slope of the regression (β2) is not significantly different from zero(Armstrong, 2012). The p-value for HML is0.514(a value greater than 5% level significance), we therefore fail to reject the null hypothesis and conclude that the slope of the regression (β3) is not significantly different from zero(Tofallis, 2009). e)Obtain a plot of the residuals for this regression. What can you tell about the residuals? Solution
In this section, we plotted a kernel density estimate for the residuals. The graph helps check whether the residuals are normally distributed or not. A bell-shaped graph shows a normally distributed dataset(Agarwal & Aluru, 2010). 0.002.004.006 Density -200-1000100200 Residuals Kernel density estimate Normal density kernel = epanechnikov, bandwidth = 26.1416 Kernel density estimate The graph above is seen to be in the shape of a bell-shaped curve, this tells us that the residuals are normally distributed. Q5: a)Estimate the following regression: yt=β0+β1x1t+β2x2t+ϵt Solution Regression analysis refers to a statistical method which applies mathematical concepts to estimate the relationship between various variables. Regression model takes the form given as follows;
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yt=β0+β1x1t+β2x2t+ϵt In our case, we sought to estimate the relationship betweenyt(dependent variable) and two independent variables (x1tandx2t).ϵtis the error term for the regression model. Model Summary ModelRR SquareAdjusted R Square Std. Error of the Estimate 1.283a.080.0671.08172 a. Predictors: (Constant), x2, x1 ANOVAa ModelSum of SquaresdfMean SquareFSig. 1 Regression14.51827.2596.204.003b Residual166.1551421.170 Total180.674144 a. Dependent Variable: y b. Predictors: (Constant), x2, x1 Coefficientsa ModelUnstandardized CoefficientsStandardized Coefficients tSig. BStd. ErrorBeta 1 (Constant).106.0911.163.247 x1.271.087.2503.094.002 x2-.128.091-.114-1.413.160 a. Dependent Variable: y b)Report and comment on the regression results. Solution
The value of R-squared as given in the model summary table is 0.080; this implies that only 8% of the variation in the dependent variable (y) is explained by the two independent variables (x1, and x2) in the model. The p-value of the F-statistics if 0.003 (a value less than 5% level of significance), we therefore reject the null hypothesis and conclude that the model is significant at 5% level of significance(Fox, 2007). Looking at individual independent variables, we see that x1is significant in the model (p-value < 0.05) while x2is insignificant in the model (p-value > 0.05). The coefficient of x1is given as 0.271; this means that a unit increase in x1would result to an increase in the dependent variable (y) by 0.271. Similarly, a unit decrease in x1would result to a decrease in the dependent variable (y) by 0.271. The coefficient of x2is given as -0.128; this means that a unit increase in x2would result to a decrease in the dependent variable (y) by 0.128. Similarly, a unit decrease in x2would result to an increase in the dependent variable (y) by 0.128. Lastly, the coefficient of the intercept is 0.106; this means that holding other factors constant (that is, zero values for x1and x2) we would expect the value of y to be 0.106. c)Conduct diagnostic checks for your regression results for: Heteroscedasticity; Solution Heteroscedasticity is basically the case where the variability of a variable is unequal across the range of values of a second variable that predicts it. That is to mean that there is no constant variance across the variables. Heteroscedasticity is one of the crucial assumptions made about regression model. Breaking this assumption would mean thatthe OLS estimators are not the Best Linear
Unbiased Estimators (BLUE) and their variance is not the lowest of all other unbiased estimators. Prob>chi2=0.0000 chi2(1)=80.08 Variables:fittedvaluesofy Ho:Constantvariance Breusch-Pagan/Cook-Weisbergtestforheteroskedasticity .hettest Applying hettest command in stata, we sought to check for heteroscedasticity using Breusch-Pagan test. Results showed that the p-value of the test was 0.000 (a value less than 5% level of significance), we therefore reject the null hypothesis ofconstantvarianceandconcludethattheregressionresultsarenot homoscedastic (no equal variance). Autocorrelation (1st order and 12th order); Solution Autocorrelation also known as serial correlation is the correlation that exists between a time series with its own past and future values. It could also refer to the correlation between members of a series of numbers arranged in time. Durbin-Watsond-statistic(3,0)=. .estatdwatson Results on autocorrelation are inconclusive since the p-value was not obtained from the results hence it is not possible to determine whether there is serial autocorrelation or not. Normality Solution
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This is another crucial assumption that needs to be made regarding data before running a regression model.Normality refers to the modeling of data in a normal distribution. r1440.9069210.4595.3100.00000 VariableObsWVzProb>z Shapiro-WilkWtestfornormaldata .swilkr UsingShapiro-Wilktest,wecheckedwhethertheregressionresultswere normally distributed. The p-value of the test was found to be 0.000 (a value less than5%levelofsignificance),wethereforerejectthenullhypothesisof normality and conclude that the regression results are not normally distributed at 5% level of significance. d)Are there any issues? How do you suggest fixing them? Solution Yes are there issues to do with the regression results. Some of the issues are; Non-normality of the data Heteroscedasticity of the dataset With the above problems, the results are bound to be biased and not reflect the true results. Hence the issues need to be fixed. For the heteroscedasticity, a robust regression need to be performed instead of the standard regression. For the non-normality, a set of transformations need to be performed to ensure normality of the dataset.
References Armstrong, J. S., 2012. Illusions in Regression Analysis.International Journal of Forecasting (forthcoming),28(3), p. 689. Fox, J., 2007. Applied Regression Analysis, Linear Models and Related Methods. Gigerenzer, G., 2004. Mindless statistics.Journal of Socio-Economics,33(5), p. 587–606. Hinkelmann, K. & Kempthorne, O., 2008. Design and Analysis of Experiments. I and II. Rubin, D. B. & Little, R. J. A., 2012. Statistical analysis with missing data. Tabachnick, B. G. & Fidell, L. S., 2007. Using Multivariate Statistics. Tofallis, C., 2009. Least Squares Percentage Regression.Journal of Modern Applied Statistical Methods,7(5), p. 526–534.