Q130·Section III (Statistics)·130 of 145The AR(2) stationarity triangleThe time series model Xt=ϕ1Xt−1+ϕ2Xt−2+ZtX_t=\phi_1X_{t-1}+\phi_2X_{t-2}+Z_tXt=ϕ1Xt−1+ϕ2Xt−2+Zt, Zt∼Z_t\simZt∼ iid N(0,σ2)N(0,\sigma^2)N(0,σ2), is stationary if: OptionsAϕ1+ϕ2<1\phi_1+\phi_2<1ϕ1+ϕ2<1, ϕ1−ϕ2<1\phi_1-\phi_2<1ϕ1−ϕ2<1, −1<ϕ1<1-1<\phi_1<1−1<ϕ1<1Bϕ1+ϕ2>1\phi_1+\phi_2>1ϕ1+ϕ2>1, ϕ2−ϕ1<1\phi_2-\phi_1<1ϕ2−ϕ1<1, −1<ϕ2<1-1<\phi_2<1−1<ϕ2<1Cϕ1+ϕ2<1\phi_1+\phi_2<1ϕ1+ϕ2<1, ϕ2−ϕ1<1\phi_2-\phi_1<1ϕ2−ϕ1<1, −1<ϕ2<1-1<\phi_2<1−1<ϕ2<1Dϕ1+ϕ2>1\phi_1+\phi_2>1ϕ1+ϕ2>1, ϕ1−ϕ2<1\phi_1-\phi_2<1ϕ1−ϕ2<1, −1<ϕ1<1-1<\phi_1<1−1<ϕ1<1Pick an option to check your answer.Show answerShow solution Report a problem with this question← Q129All questionsQ131 →Keyboard: A–D answer · S solution · ←/→ previous/next