推 bookticket:感謝版主:) 05/04 03:11
※ 引述《bookticket ()》之銘言:
: 學校最近使用Ruey S. Tsay (蔡瑞胸)(中研院院士)
: 的Analysis of Financial Time Series
: 此書在chapter2 section6 p56下方到p57上方
: 提到ARMA(1,1)模型: r -ψ r =ψ + a - θ a
: t 1 t-1 0 t 1 t-1
r -ψ r =ψ + a - θ a
t 1 t-1 0 t 1 t-1
=> (1-ψ B) r =ψ + (1-θ B ) a , where B is the backshift operator
1 t 0 1 t
If ψ = θ =θ
1 1
=> r = ψ + a
t 0 t
---------
1-θB
Then the process reduces to a white noise series
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