目的:1、正确使用EVIEWS
2、会使用OLS和WLS,Goldfeld-Quandt检验
3、能根据计算结果进行异方差分析和出现异方差性后的补救。
3、数据为demo data1
实例:某市人均储蓄与人均收入的关系分析(异方差性检验及补救)
根据某市1978-1998年人均储蓄与人均收入的数据资料(见下表),其中X为人均收入(元),Y为人均储蓄(元),经分析人均储蓄受人均收入的线性影响,可建立一元线性回归模型进行分析。
obs | X | Y |
1978 | 590.2000 | 107.0000 |
1979 | 664.9400 | 123.0000 |
1980 | 809.5000 | 159.0000 |
1981 | 875.5400 | 189.0000 |
1982 | 991.2500 | 233.0000 |
1983 | 1109.950 | 312.0000 |
1984 | 1357.870 | 401.0000 |
1985 | 1682.800 | 522.0000 |
1986 | 1890.580 | 664.0000 |
1987 | 2098.250 | 871.0000 |
1988 | 2499.580 | 1033.000 |
1989 | 2827.730 | 1589.000 |
1990 | 3084.170 | 2209.000 |
1991 | 3462.710 | 2878.000 |
1992 | 3932.520 | 3722.000 |
1993 | 5150.790 | 5350.000 |
1994 | 7153.350 | 8080.000 |
1995 | 9076.850 | 11758.00 |
1996 | 10448.21 | 15839.00 |
1997 | 11575.48 | 18196.00 |
1998 | 12500.84 | 20954.00 |
1、用OLS估计法估计参数
设模型为:
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运行EVIEWS软件,并输入数据,得计算结果如下:
Dependent Variable: Y Method: Least Squares Date: 10/11/05 Time: 23:10 Sample: 1978 1998 Included observations: 21 Variable Coefficient Std. Error t-Statistic Prob. C -2185.998 339.9020 -6.431262 0.0000 X 1.684158 0.062166 27.09150 0.0000 R-squared 0.974766 Mean dependent var 4533.238 Adjusted R-squared 0.973438 S.D. dependent var 6535.103 S.E. of regression 1065.086 Akaike info criterion 16.86989 Sum squared resid 21553736 Schwarz criterion 16.96937 Log likelihood -175.1338 F-statistic 733.9495 Durbin-Watson stat 0.293421 Prob(F-statistic) 0.000000
2、异方差检验
(1)Goldfeld-Quandt检验
在Procs菜单项选Sort series项,出现排序对话框,输入X,OK。
在Sample菜单里,将时间定义为1978-1985,用OLS方法计算得如下结果:
Y = -145.441495 + 0.3971185479*X
(-8.730234) (25.42693)
R-squared=0.990805 Sum squared resid1=15.12284
Dependent Variable: Y Method: Least Squares Date: 10/11/05 Time: 23:25 Sample: 1978 1985 Included observations: 8 Variable Coefficient Std. Error t-Statistic Prob. C -145.4415 16.65952 -8.730234 0.0001 X 0.397119 0.015618 25.42693 0.0000 R-squared 0.990805 Mean dependent var 255.7500 Adjusted R-squared 0.989273 S.D. dependent var 146.0105 S.E. of regression 15.12284 Akaike info criterion 8.482607 Sum squared resid 1372.202 Schwarz criterion 8.502468 Log likelihood -31.93043 F-statistic 646.5287 Durbin-Watson stat 1.335534 Prob(F-statistic) 0.000000
在Sample菜单里,将时间定义为1991-1998,用OLS方法计算得如下结果:
Y = -4602.367144 + 1.952519317*X
(-5.065962) (18.40942)
R-squared=0.982604 Sum squared resid2=5811189.
Dependent Variable: Y Method: Least Squares Date: 10/11/05 Time: 23:29 Sample: 1991 1998 Included observations: 8 Variable Coefficient Std. Error t-Statistic Prob. C -4602.367 908.4882 -5.065962 0.0023 X 1.952519 0.106061 18.40942 0.0000 R-squared 0.982604 Mean dependent var 10847.12 Adjusted R-squared 0.979705 S.D. dependent var 6908.102 S.E. of regression 984.1400 Akaike info criterion 16.83373 Sum squared resid 5811189. Schwarz criterion 16.85359 Log likelihood -65.33492 F-statistic 338.9068 Durbin-Watson stat 0.837367 Prob(F-statistic) 0.000002
求F统计量:
,查F分布表,给定显著性水平
,得临界值
,比较
>
,拒绝原假设
,表明随机误差项显著的存在异方差。
3、异方差的修正
(1)WLS估计法。
首先生成权函数
,然后用OLS估计参数,
Y = -2262.639946 + 1.566910934*X
Dependent Variable: Y Method: Least Squares Date: 10/12/05 Time: 08:07 Sample: 1978 1998 Included observations: 21 Weighting series: W Variable Coefficient Std. Error t-Statistic Prob. C -2262.640 131.2507 -17.23907 0.0000 X 1.566911 0.057637 27.18590 0.0000 Weighted Statistics R-squared 0.961501 Mean dependent var 2183.201 Adjusted R-squared 0.959475 S.D. dependent var 2104.209 S.E. of regression 423.5951 Akaike info criterion 15.02583 Sum squared resid 3409224. Schwarz criterion 15.12530 Log likelihood -155.7712 F-statistic 474.5211 Durbin-Watson stat 0.354490 Prob(F-statistic) 0.000000 Unweighted Statistics R-squared 0.962755 Mean dependent var 4533.238 Adjusted R-squared 0.960794 S.D. dependent var 6535.103 S.E. of regression 1293.978 Sum squared resid 31813191 Durbin-Watson stat 0.224165
(2)对数变换法。
用GENR生成LY和LX序列,用OLS方法求LY 对LX的回归,结果如下:
LY = -6.839135503 + 1.787148637*LX
Dependent Variable: LY Method: Least Squares Date: 10/12/05 Time: 00:05 Sample: 1978 1998 Included observations: 21 Variable Coefficient Std. Error t-Statistic Prob. C -6.839136 0.237565 -28.78845 0.0000 LX 1.787149 0.030033 59.50680 0.0000 R-squared 0.994663 Mean dependent var 7.195082 Adjusted R-squared 0.994382 S.D. dependent var 1.746173 S.E. of regression 0.130880 Akaike info criterion -1.138677 Sum squared resid 0.325463 Schwarz criterion -1.039199 Log likelihood 13.95611 F-statistic 3541.059 Durbin-Watson stat 0.642916 Prob(F-statistic) 0.000000
比较方法(1)和(2),可以看出X与Y在对数线性回归下拟合效果较好。原因是Y的曲线呈对数型图形有关。



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