Questions from Econometrics


Q: Suppose that C is an n * n symmetric idempotent matrix with

Suppose that C is an n * n symmetric idempotent matrix with rank r, and let V ∼ N (0n, In). a. Show that C = AA′, where A is n * r with A′A = Ir. b. Show that A′V ∼ N (0r, Ir). c. Show that V′CV ∼ x2r...

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Q: a. Show that B∼Eff.GMM is the efficient

a. Show that B∼Eff.GMM is the efficient GMM estimator—that is, that B∼Eff.GMM in Equation (19.66) is the solution to Equation (19.65). b. Show...

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Q: Consider the problem of minimizing the sum of squared residuals, subject

Consider the problem of minimizing the sum of squared residuals, subject to the constraint that Rb = r, where R is q * (k + 1) with rank q. Let B∼ be the value of b that solves the...

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Q: Consider the regression model Y = XB + U. Partition X

Consider the regression model Y = XB + U. Partition X as [X1 X2] and B as [B′1 B′2]′, where X1 has k1 columns and X2 has k2 columns. Suppose that...

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Q: Consider the panel data model Yit = Xit + i

Consider the panel data model Yit = Xit + i + uit, where all variables are scalars. Assume that assumptions 1, 2, and 4 in Key Concept 10.3 hold and strengthen ass...

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Q: This exercise takes up the problem of missing data discussed in Section

This exercise takes up the problem of missing data discussed in Section 9.2. Consider the regression model Yi = Xib + ui, i = 1 … n, where all variables are scalars and the constan...

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Q: Suppose Yi is distributed i.i.d. N (

Suppose Yi is distributed i.i.d. N (0, 2) for i = 1, 2, …, n. a. Show that E (Y2i /2) = 1 b. Show that c. Show that E(W) = n...

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Q: Consider the regression model in matrix form Y = XB + WG

Consider the regression model in matrix form Y = XB + WG + U, where X and W, are matrices of regressors and B and G are vectors of unknown regression coefficients. Let X∼ = MWX and...

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Q: Consider the homoskedastic linear regression model with two regressors, and let

Consider the homoskedastic linear regression model with two regressors, and let rX1, X2 = corr(X1, X2). Show that as n increases.

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Q: Suppose that a sample of n = 20 households has the sample

Suppose that a sample of n = 20 households has the sample means and sample covariances below for a dependent variable and two regressors: a. Calculate the OLS estimates of 0, ï&...

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