本文在有限样本情况下,用Monte Carlo方法模拟了具有GJR—GARCH—skewt误差项时间序列的ADF单位根检验.分析模型中误差项的波动、条件分布中参数的设定、样本容量及杠杆效应对临界值的影响.结果显示.随着波动的持久性加强,使用经典ADF单位根检验的Zi、ZpFuller临界值将降低检验的有效性.
We simulate the finite-sample ADF unit root test with data generated from GJR- GARCH-skewt error processing by Monte Carlo simulation,and discuss the volatility of disturbance, parameters in conditional distribution,sample length and lever effect. The result suggests that, along with strengthens of volatility durability, the validity of examination will be reduced by the Fuller critical values of Zl,Zpwhich were got by ADF test.