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第一个是LM test,请问这是在arch模型之前做来分析数据符不符合arch,还是之后做来分析该模型效果的呢?
我是先reg了一下,然后 用的这个指令,estat archlm, lags(1)
LM test for autoregressive conditional heteroskedasticity (ARCH)
---------------------------------------------------------------------------
lags(p) | chi2 df Prob > chi2
-------------+-------------------------------------------------------------
1 | 3.805 1 0.0511
---------------------------------------------------------------------------
H0: no ARCH effects vs. H1: ARCH(p) disturbance
出来的结果要用哪个数据和那个数据比较呀?我看到有些课件上说T*R2与X2 0.05(q)比较吗? 可是里面的0.05是怎么得出的呀?
第二个是estate ic 得出的aic和bic值,这样的话正常吗?
estat ic
Akaike's information criterion and Bayesian information criterion
-----------------------------------------------------------------------------
Model | Obs ll(null) ll(model) df AIC BIC
-------------+---------------------------------------------------------------
. | 268 . 927.1871 3 -1848.374 -1837.601
-----------------------------------------------------------------------------
Note: N=Obs used in calculating BIC; see [R] BIC note
aic和bic要怎么看呀?越小越好,双方越接近越好吗?
另外就是ADF检验是检验单位根的吗?
dfuller D.lprice, regress lag(1)
Augmented Dickey-Fuller test for unit root Number of obs = 266
---------- Interpolated Dickey-Fuller ---------
Test 1% Critical 5% Critical 10% Critical
Statistic Value Value Value
------------------------------------------------------------------------------
Z(t) -11.469 -3.459 -2.879 -2.570
------------------------------------------------------------------------------
MacKinnon approximate p-value for Z(t) = 0.0000
------------------------------------------------------------------------------
D2.lprice | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
lprice |
LD. | -.9795227 .0854089 -11.47 0.000 -1.147695 -.8113504
LD2. | .0135429 .0614939 0.22 0.826 -.1075401 .1346258
|
_cons | -.0002203 .0004753 -0.46 0.643 -.0011562 .0007156
------------------------------------------------------------------------------
要怎么看有没有单位根呢? LD的t值比-2.879小好多,是说明有单位根吗?那是不是就不能用arch了呀?
还有就是残差检验要怎么检验呀?
stata 总是说找不到e2,要怎么生成呢?
抱歉啊, 最近刚接触stata,太菜鸟了,希望有大神可以耐心指点一下!拜托了!
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