Exercise 7.9.8. For an AR(2) process, use the YuleWalker equations, with y() replacing y() to obtain estimates 1 = (1) (1 (1)) 1 (1)2

Exercise 7.9.8. For an AR(2) process, use the Yule–Walker equations, with σˆy(·)

replacing σy(·) to obtain estimates

φˆ1 =

ρˆ (1) (1−ρˆ (1))

1−ρˆ (1)2 and

φˆ2 =

ρˆ (2)−ρˆ (1)2 1−ρˆ (1)2 .