, (TS -) , , , (DS -). - . TS - DS - , .
TS - , . DS - ( ) , , , , , .
TS - , DS - , . , - (, ARMA) . ARIMA . , ( ) .
[6], DS - , ( ), . , TS - , , , : , ( ).
DS - .3.14, - .3.19.. , , DS (..3.14).
) )
.3.19. DS - () TS - ()
TS- .3.19., , TS - (..3.15).
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, (TS - DS ) . , . TS DS , , ( ), .
, DS TS , () DS, TS - . DS - (unit root), .. z = 1 (z) = 0, (B) B Xt
, () TS, DS -. X t z = 1 蠠 θ(z)=0, θ() D t = θ(B) a t D X t = X t - X t- 1 X t.
, TS DS [5].
Xt = α + ρ Xt 1 +β t + at. (3.14)
(3.14) TS DS , (3.11), (3.12) , :
H 0: DS, ρ = 1; β = 0;
H 1: TS, |ρ| < 1 ( at , ).
. :
Xt = α + ρ Xt 1 +β t + at Xt = α + Xt 1 + at.
F -. - . - , . , t DS (DS -); TS (TS -). - , (, ).
(3.14),
Xt = α + ρ Xt 1 + at, (3.15)
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.. .
H 0: DS, ρ = 1;
H 1: TS, |ρ| < 1.
, ρ = 1 t -. (3.15) : Xt 1,
Δ Xt = α + (ρ 1) Xt 1 + at, t = 1,..., N. (3.16)
ρ 1 = γ,
Δ Xt = α + γ Xt 1 + at, (3.17)
H 0: γ = 0;
H 1: γ < 0.
t -. H 0 () α*, γ* (3.17) α γ. |γ*| < σγ* q 100 p /2, σγ* - γ; q 100 p /2 - N 1 .
H 0 . , γ*/ σγ* N 1 - , DS -. , -. 100 p /2- , -. -, , γ*/ σγ* , -.
Δ Xt = α + γ Xt 1 +β t + at. (3.18)
H 0: β = 0; γ = 0 → DS;
H 1: γ < 0 → TS.
H 0 - α, γ, β (3.18), ,
up, , 2 N - 2. u < up H 0 . , , , u DS - . u . .3.3 F - .
3.3 -
- | ||
25 50 100 ∞ | 7,24 6,73 6,49 6,25 | 3,44 3,20 3,09 3,00 |
, . , N = 25 3,44 < u < 7,24 , H 0 H 1. , 7,24, , H 0 .
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.3.20, [5], -. .3.20 , - . , F - , : F - (, b), , TS, DS.
.3.20. -
, - , , .
, (3.17) α ≠ 0, - . (α = 0) - . (3.18): - , α, β. , - , . , , - , , .
, - () , x t DS (DS -); TS (TS -). - , AR (1) (, ). , . (SM , statistical model; DGP , data generating process) [6].
1) Xt ( ),
SM: Δ Xt = α + γ Xt 1 +β t + at, t = 2,..., T,
DGP: Δ Xt = α + at, t = 2,..., T.
(3.18); - . at , .
, t - t γ H 0: γ = 0. t , , DGP. DS - , t γ < t .
2) Xt ( ) ,
SM: Δ Xt = α + γ Xt 1 + at, t = 2,..., T, (3.19)
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DGP: Δ Xt = at, t = 2,..., T.
SM t - t γ H 0: γ = 0. t , , DGP ( ). DS - , t γ < t .
3) , Xt ( ) ,
SM: Δ Xt = γ Xt 1 + at, t = 2,..., T, (3.20)
DGP: Δ Xt = at, t = 2,..., T.
SM, t - t γ H 0: γ = 0. t , , DGP ( ). DS - , t γ < t .
t - [3]
t = k 0 + k 1 / (N + 1) + k 2 / (N + 1)2, (3.21)
k 0, k 1, k 2 . .3.4.
3.4 k 0, k 1, k 2
(3.18) | (3.19) | (3.20) | ||||
= 0,01 | = 0,05 | = 0,01 | = 0,05 | = 0,01 | = 0,05 | |
k 0 | -3,96 | -3,41 | -3,43 | -2,86 | -2,57 | -1,94 |
k 1 | -8,35 | -4,04 | -6,0 | -2,74 | -1,96 | -0,40 |
k 2 | -47,44 | -17,83 | -29,25 | -8,36 | -10,04 | 0 |
3.5. - ARFIMA
ARIMA, (3.3)
d , 1 2. , d . d, 2, .
, . (autoregressive fractionally integrated moving average - ARFIMA) , -. , ARFIMA, .