Hi all Just a couple of queries on CT3-13: 1) In the middle of p22 - how does result (*) follow from the fact that beta-hat and sigma-hat^2 are independent? 2) On page 23, in the example, in part (a) of the solution, where does the 'plus-or-minus' sign come from? Also in CT3-14: 3) On page 13 it states that x2 has a chi-squared distribution with parameter n3 - n1, why is the parameter not n3 + n1 like in question 14.9? Many thanks
1) It follows from the definition of t distribution this requires standard normal variable and the chi-square variable to be independent. 2) Its confidence interval for beta, you should be familiar with this from chapter 11. 3) In question 14.9 there is an addition of two independent chi-square, whereas here its subtraction.
