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Q46Section ST (Statistics (Q11–Q65))46 of 65

Joint region and coefficient covariance

Consider the simple linear regression model yi=β0+β1xi+ϵiy_i = \beta_0 + \beta_1 x_i + \epsilon_i, i=1,2,…,ni = 1, 2,…, n, where β0,β1\beta_0, \beta_1 are unknown parameters, ϵi\epsilon_i's are uncorrelated random errors with mean 0 and finite variance σ2>0\sigma^2 > 0. Let β^i\hat\beta_i be the least squares estimator of βi\beta_i, i=0,1i = 0,1. Consider the following statements: (I) A 95% joint confidence region for (β0,β1)(\beta_0, \beta_1) is the region bounded by an ellipse. (II) The expression for covariance between β^0\hat\beta_0 and β^1\hat\beta_1 does not involve σ2\sigma^2. Which of the above statements is/are true?

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