人大时间序列课后习题答案 第二章P34
1、(1)因为序列具有明显的趋势,所以序列非平稳。
(2)样本自相关系数:
,nk
(x,x)(x,x),,ttk,(k),1tˆ, ,,kn(0),2(x,x),t,1t
n11 x,x,(1,2,?,20),10.5,tn20,1t
2012 ,(0),(x,x),35 ,t20t,1
191 ,(1),(x,x)(x,x),29.75 ,tt,119t,1
181 ,(2),(x,x)(x,x),25.9167 ,tt,218t,1
171 ,(3),(x,x)(x,x),21.75 ,tt,317t,1
(4)=17.25 (5)=12.4167 (6)=7.25 ,,,
=0.85(0.85) =0.7405(0.702) =0.6214(0.556) ,,,231
=0.4929(0.415) =0.3548(0.280) =0.2071(0.153) ,,,456注:括号内的结果为近似公式所计算。
(3)样本自相关图:
Autocorrelation Partial Correlation AC PAC Q-Stat Prob
. |*******| . |*******| 1 0.850 0.850 16.732 0.000
. |***** | . *| . | 2 0.702 -0.076 28.761 0.000
. |**** | . *| . | 3 0.556 -0.076 36.762 0.000
. |*** | . *| . | 4 0.415 -0.077 41.500 0.000
. |**. | . *| . | 5 0.280 -0.077 43.800 0.000
. |* . | . *| . | 6 0.153 -0.078 44.533 0.000
. | . | . *| . | 7 0.034 -0.077 44.572 0.000
. *| . | . *| . | 8 -0.074 -0.077 44.771 0.000
. *| . | . *| . | 9 -0.170 -0.075 45.921 0.000
.**| . | . *| . | 10 -0.252 -0.072 48.713 0.000
.**| . | . *| . | 11 -0.319 -0.067 53.693 0.000
***| . | . *| . | 12 -0.370 -0.060 61.220 0.000 该图的自相关系数衰减为0的速度缓慢,可认为非平稳。
2m,,ˆ,k,,LBnn,,(2)4、 ,,,nk,,1k,,
LB(6)=1.6747 LB(12)=4.9895
22 (6)=12.59 (12)=21.0 ,,0.050.05
显然,LB统计量小于对应的临界值,该序列为纯随机序列。
第三章P97
1、解: E(x),0.7*E(x),E(,)tt,1t
(1,0.7)E(x),0E(x),0tt
(1,0.7B)x,,tt
,122 x,(1,0.7B),,(1,0.7B,0.7B,?),ttt
122 Var(x),,,1.9608,t,,1,0.49
2 ,,,,,0.49,,021022
2、解:对于AR(2)模型:
,,,,,,,,,,,,,0.5,11021121, ,,,,,,,,,,,,,,0.321120112,
,,7/15,1解得: ,,,1/152,
3、解:根据该AR(2)模型的形式,易得: E(x),0t
原模型可变为: x,0.8x,0.15x,,tt,1t,2t
1,,22(), Varx,t(1,)(1,,)(1,,),,,,,21212
(1,0.15)22, =1.9823 ,,(1,0.15)(1,0.8,0.15)(1,0.8,0.15)
,,,,,,/(1,),0.6957,,0.6957,,112111,,,,,,,,, ,,,0.4066,,,0.15,,21120222
,,,,,,,,,,,0.2209,03122133,,
4、解:原模型可变形为:
2(1,B,cB)x,, tt
由其平稳域判别条件知:当,且时,模型平稳。 |,|,1,,,,1,,,,122121
由此可知c应满足:,且 |c|,1c,1,1c,1,1
即当,1
证明
住所证明下载场所使用证明下载诊断证明下载住所证明下载爱问住所证明下载爱问
:已知原模型可变形为:
23(1,B,cB,cB)x,, tt
322 其特征方程为: ,,,,c,,c,(,,1)(,,,,c),0
不论c取何值,都会有一特征根等于1,因此模型非平稳。
22,,Var(x),,/(1,,)6、解:(1)错,。 1t,0
22E[(x,,)(x,,)],,,,,,,,/(1,,) (2)错,。 tt,,111011
lˆx(l),,x (3)错,。 T1T
e(l),,,G,,G,,?,G, (4)错, TT,l1T,l,12T,l,2l,1T,1
2l,1,,,,,,,,?,,, , T,l1T,l,11T,l,21T,1
l21[1,],1221ˆlim[,()],lim[()],lim,VarxxlVarel,, (5)错,。 T,lTT,,22l,,l,,l,,1,1,,,11
2,,1,1,4,,11,,7、解: ,,,,,1112,2,1,11
。 MA(1)模型的表达式为:x,,,,ttt,1
8、解: E(x),,/(1,,),10/(1,0.5),20t01
23(1,0.5B)(x,20),(1,0.8B,CB), 原模型可变为: tt
23(1,0.8B,CB)x,20,, tt(1,0.5B)
23 显然,当能够整除1,0.5B时,模型为MA(2)模型,由此1,0.8B,CB
23得B,2是,0的根,故C,0.275。 1,0.8B,CB
9、解:: E(x),0t
2222Var(x),(1,,,,),,1.65, t,,12
,,,,,,0.98112, ,,,,0.59391221.65,,1,,12
,,0.42, ,,0,k,3,,,0.2424k222,,1.651,,12
10、解:(1) x,,,C(,,,,?)ttt,1t,2
x,,,C(,,,,?)t,1t,1t,2t,3
,x,,,t,1t,1 x,,,C,,,x,,,(C,1),,,ttt,1t,1tt,1C,,
即 (1,B)x,[1,(C,1)B], tt
显然模型的AR部分的特征根是1,模型非平稳。
(2) 为MA(1)模型,平稳。 y,x,x,,,(C,1),ttt,1tt,1
,,C,11, ,,1221,,C,2C,21
11、解:(1),模型非平稳; |,|,1.2,12
1.3738 -0.8736 ,,,,12
2),,,模型平稳。 (|,|,0.3,1,,,,0.8,1,,,,,1.4,122121
0.6 0.5 ,,,,12
(3),,,模型可逆。 |,|,0.3,1,,,,0.6,1,,,,,1.2,122121
0.45,0.2693i 0.45,0.2693i ,,,,12
(4),,,模型不可逆。 |,|,0.4,1,,,,,0.9,1,,,,1.7,122121
0.2569 -1.5569 ,,,,12
(5),模型平稳;0.7 |,|,0.7,1,,11
,模型可逆;0.6 |,|,0.6,1,,11
(6),,,模型非平稳。 |,|,0.5,1,,,,,0.3,1,,,,1.3,122121
0.4124 -1.2124 ,,,,12
,模型不可逆;1.1 |,|,1.1,1,,11
12、解: (1,0.6B)x,(1,0.3B),tt
22 x,(1,0.3B)(1,0.6B,0.6B,?),tt
223 ,(1,0.3B,0.3*0.6B,0.3*0.6B,?),t
,1j, ,,,0.3*0.6,,tt,j1j,
j,1 ,G,0.3*0.6 G,10j
213、解: E[,(B)x],E[3,,(B),],(1,0.5)E(x),3ttt
E(x),12t
14、证明:; ,,,(0)/,(0),10
,,,,,(,)(1,)(1)0.25(1,0.5*0.25)1111, ,,,,0.27122,,,,(0)1,,21,0.25,2*0.5*0.25111
,,,,,0.5,k,2k1k,1k,1
15、解:(1)错;(2)对;(3)对;(4)错。
16、解:(1), x,10,0.3*(x,10),,x,9.6tt,1tT
ˆ x(1),E(x),E[10,0.3*(x,10),,],9.88Tt,1TT,1
ˆ x(2),E(x),E[10,0.3*(x,10),,],9.964Tt,2T,1T,2
ˆ x(3),E(x),E[10,0.3*(x,10),,],9.9892Tt,3T,2T,3
j 已知AR(1)模型的Green函数为:, G,,j,1,2,?1j
2 e(3),G,,G,,G,,,,,,,,,T0t,31t,22t,1t,31t,21t,1
22 Var[e(3)],(1,0.3,0.09)*9,9.8829T
[9.9892-1.96*,9.9892,1.96*] x的95,的置信区间:9.88299.8829t,3
即[3.8275,16.1509]
ˆ (2) ,,x,x(1),10.5,9.88,0.62T,1T,1T
ˆ x(1),E(x),0.3*0.62,9.964,10.15T,1t,2
ˆ x(2),E(x),0.09*0.62,9.9892,10.045 T,1t,3
2 Var[e(2)],(1,0.3)*9,9.81T,2
x[10.045-1.96×,10.045,1.96*] 的95,的置信区间:9.819.81t,3
即[3.9061,16.1839]