Consider the simple regression model yi= B1+B2xi2+ei . Suppose N=5 and the values of xi2 are (1,2,3,4,5). Let the true values of the parameters be B1=1 , B2=1 . Let the true random error values, which are never known in reality, be ei= (1,-1,0,6,-6) .
a) Calculate the values of yi
b) Compute the OLS estimates of the parameter
c) Compute the least squares residuals, e1 , e2 , e3 , e4 , e5 . What's their sum?
d) It is hypothesized that the data are Heteroskedastic with the variance of the 1st 3 random errors being theta21 and the variance of the last 2 random errors being theta22. We regress the squared residuals ei2 on an indicator variable zi , where zi = 0 for i=1,2,3 and the zi=1 for i=4,5. this regression, ei2=alpha1 + alpha2zi+vi , has an R2 = .8108. Use this value to carry out the LM test for Heteroskedasticity at the 5% level of significance
Consider the simple regression model yi= B1+B2xi2+ei . Suppose N=5 and the values of xi2 are...
Consider the model, Yi = Bo + B1 X1,1 + B2 X2,1 + Uj, where sorting the residuals based on the X1,; and X2,1 gives: X1 X2 Goldfeld-Quandt Statistic 1.475 0.843 If there is heteroskedasticity present at the 5% critical-F value of 1.624, then choose the most appropriate heteroskedasticity correction method. O A. Not enough information. OB. White's heteroskedastic-consistent standard errors C. Heteroskedastic correction based on X1. Ο Ο Ο D. Heteroskedastic correction based on X2. E. No heteroskedastic correction...
4. Consider the regression model, y1B22+ BKiK+ei -.. where errors may be heteroskedastic. Choose the most incorrect statement (a) The OLS estimators are consistent and unbiased (b) We should report the OLS estimates with the robust standard errors (c) The Gauss-Markov theorem may not apply (d) The GLS cannot be used because we do not know the error variances in practice (e) We should take care of heteroskedasticity only if homoskedasticity is rejected Consider the regression model, +BKIK+et e pet-1+...
Consider the least-squares residuals ei-yi-yi, 1, 2, . . . , linear regression model. Find the variance of the residuals Var(e). Is the vari- ance of the residuals a constant? Discuss. n,from the simple
1. Consider a regression model Yi = x;ß +ei, i = 1,...,n. You estimate this model using the OLS estimator. (a) Present and discuss assumptions for the OLS estimation.
5) Consider the simple linear regression model N(0, o2) i = 1,...,n Let g be the mean of the yi, and let â and ß be the MLES of a and B, respectively. Let yi = â-+ Bxi be the fitted values, and let e; = yi -yi be the residuals a) What is Cov(j, B) b) What is Cov(â, ß) c) Show that 1 ei = 0 d) Show that _1 x;e; = 0 e) Show that 1iei =...
2. Consider a simple linear regression model for a response variable Yi, a single predictor variable ri, i-1,... , n, and having Gaussian (i.e. normally distributed) errors Ý,-BzitEj, Ejį.i.d. N(0, σ2) This model is often called "regression through the origin" since E(Yi) 0 if xi 0 (a) Write down the likelihood function for the parameters β and σ2 (b) Find the MLEs for β and σ2, explicitly showing that they are unique maximizers of the likelihood function. (Hint: The function...
2. Consider a simple linear regression i ion model for a response variable Y, a single predictor variable ,i1.., n, and having Gaussian (i.e. normally distributed) errors: This model is often called "regression through the origin" since E(X) = 0 if xi = 0 (a) Write down the likelihood function for the parameters β and σ2 (b) Find the MLEs for β and σ2, explicitly showing that they are unique maximizers of the likelihood function Hint: The function g(x)log(x) +1-x...
1. Consider the simple linear regression model: Ү, — Во + B а; + Ei, where 1, . . , En are i.i.d. N(0,02), for i1,2,... ,n. Let b1 = s^y/8r and bo = Y - b1 t be the least squared estimators of B1 and Bo, respectively. We showed in class, that N(B; 02/) Y~N(BoB1 T;o2/n) and bi ~ are uncorrelated, i.e. o{Y;b} We also showed in class that bi and Y 0. = (a) Show that bo is...
Question 1 Consider the simple regression model (only one covariate): y= BoB1 u Let B1 be the OLS estimator of B1. a) What are the six assumptions needed for B1 to be unbiased, have a simple expression for its variance, and have normal distribution? (3 points) b) Under Assumptions 1-6, derive the distribution of B1 conditional on x\,..., xn. (3 points) In lecture we described how to test the null hypothesis B1 bo against the alternative hypothesis B1 bo, where...
Consider the following simple regression model: a. Suppose that OLS assumptions 1 to 4 hold true. We know that homoskedasticity assumption is statedas: Var[UjIx] = σ2 for all i Now, suppose that homoskedasticity does not hold. Mathematically, this is expressed as In other words, the subscript i in σ12 means that the conditional variance of errors for each individual i is different. Under heteroskedasticity, we can derive the expression for the variance of Var(B) as SST Where SSTx is the...