广东商学院2012________模拟试题上机操作答案



【1.单位根检验】
打开GJ的图像,它不是从原点出发,故有截距有常数项,故填上c;由于它有上升和下降2个趋势,互相抵消,趋势为t=0;判断滞后阶数:
根据图像判断出它有截距但没趋势,故选择
看图中阴影部分,可以得出它是2阶滞后,故k=2.所以表格填上(c,0,2)。其他空格数据亦填上。
看上图,概率42.06%>最大的10%,则为不平稳。
接着做GJ的一阶差分△gj。输入命令genr dgj=d(gj,1)回车,打开dgj表格,依然先看图像,再进行单位根检验(注意它无截距也无趋势,选择)。
故填表为(0,0,1)并由上图可知,0.41%<最小的1%,则说明它在1%显著水平下是平稳的,5%、10%就更不用说,都是平稳的。故在这行最后一栏填上【平稳﹡﹡﹡】
最后的结论就说:股票价格gj在1%的显著性水平下是一阶单整的,或△gj在1%显著水平下平稳。
其他的2项填表和结论步骤一样。
注意:△hl单位根检验时候有下图,概率2.93%>1%但<5%,故在5%的水平下一阶单整
【2.格兰杰因果检验】
根据检验变量组成group【HL、DGJ、DR】如下图
,
在view下选择格兰杰检验选项如下图,根据题目先选择1阶滞后,得出结论:根据对应表格填好数据。
在滞后一期时,以10%显著性水平下,伴随概率P值中有个为0.0873小于10%,拒绝原假设,DR是DGJ的格兰杰原因,但DGJ不是DR的格兰杰原因(伴随概率为0.7984)。
而若以5%显著性水平下,P值全部大于5%,接受原假设,互相不为格兰杰原因。
同样,在滞后二期时,以10%显著性水平下,P值全部大于10%,接受原假设,互相不为格兰杰原因。
【插曲:如何选择滞后期数(写论文有用)】点击View下面的Lag Structure,再选最后一个,点OK。
由上图可知,选滞后期数的标准有6个,其中SC和HQ的一阶带星号,FPE和AIC的二阶带星号,LR的六阶带星号,而最多的是有2个星号的(一阶滞后和二阶滞后都可),故可选择滞后期数为2.。
【3. VAR估计】
看第一行有哪些因变量(DGJ、DR、HL),选择三者,如下图:

不用改数据,直接点击确定得下图:根据数据填表。
66个样本,t值大于1.6或小于-1.6则显著(每一项第三行中括号里面的是t值)
DGJ受到DGJ(-1)、DGJ(-2)、DR(-1)的显著影响;
DR受到DR(-1)、DR(-2)的显著影响;
HL受到HL(-1)、HL(-2)、c的显著影响。
【4.各变量对HL冲击的脉冲响应】
在上表的基础上点击View下面的Impulse Response,弹出对话框。因为是对HL的冲击,故在右下图的右上方框框阴影[dgj dr]删去,只剩下hl,点击确定得趋势图(只解释蓝色线,不管红色线,用语言描述蓝色线走势即为本题的结果分析)。

再次点击View下面的Impulse Response,弹出对话框,右上角还是hl,但左上角改为Table,点击确定得脉冲响应函数的数据,据此填写表格。
结果分析:例:HL受到DGL脉冲影响,一到二期上升,二到八期下降,后趋向平稳;DR、HL同样可得出。
【5. HL的方差分解】
点击View下面的Variance Decomposition,弹出对话框,同样把右上角框框中阴影[dgj dr]删去,只剩下hl。
得出表格。结论为:HL变动的主要原因是受到它自身的冲击,其他两个原因DGJ、DR的影响微乎其微。
(看后三列,DGJ、DR的都是0点几或1点几的,而HL最低都97多,最高99多,故主要受其自身影响)

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