一、研究目的和要求
表1列出了1998年我国主要制造工业销售收入与销售利润的统计资料,请利用统计软件Eviews建立我国制造业利润函数模型,检验其是否存在异方差,并加以补救。
表 1 我国制造工业1998年销售利润与销售收入情况
行业名称 | 销售利润Y | 销售收入X |
食品加工业 | 187.25 | 3180.44 |
食品制造业 | 111.42 | 1119.88 |
饮料制造业 | 205.42 | 14. |
烟草加工业 | 183.87 | 1328.59 |
纺织业 | 316.79 | 3862.9 |
服装制品业 | 157.7 | 1779.1 |
皮革羽绒制品 | 81.7 | 1081.77 |
木材加工业 | 35.67 | 443.74 |
家具制造业 | 31.06 | 226.78 |
造纸及纸品业 | 134.4 | 1124.94 |
印刷业 | 90.12 | 499.83 |
文教体育用品 | 54.4 | 504.44 |
石油加工业 | 194.45 | 2363.8 |
化学原料纸品 | 502.61 | 4195.22 |
医药制造业 | 238.71 | 12.1 |
化学纤维制品 | 81.57 | 779.46 |
橡胶制品业 | 77.84 | 692.08 |
塑料制品业 | 144.34 | 1345 |
非金属矿制品 | 339.26 | 2866.14 |
黑色金属冶炼 | 367.47 | 3868.28 |
有色金属冶炼 | 144.29 | 1535.16 |
金属制品业 | 201.42 | 1948.12 |
普通机械制造 | 354.69 | 2351.68 |
专用设备制造 | 238.16 | 1714.73 |
交通运输设备 | 511.94 | 4011.53 |
电子机械制造 | 409.83 | 3286.15 |
电子通讯设备 | 508.15 | 4499.19 |
仪器仪表设备 | 72.46 | 663.68 |
EVIEWS 软件估计参数结果如下
Dependent Variable: Y | ||||
Method: Least Squares | ||||
Date: 06/01/16 Time: 20:16 | ||||
Sample: 1 28 | ||||
Included observations: 28 | ||||
Variable | Coefficient | Std. Error | t-Statistic | Prob. |
C | 12.03349 | 19.51809 | 0.616530 | 0.5429 |
X | 0.104394 | 0.008442 | 12.36658 | 0.0000 |
R-squared | 0.854694 | Mean dependent var | 213.4639 | |
Adjusted R-squared | 0.849105 | S.D. dependent var | 146.4905 | |
S.E. of regression | 56.90455 | Akaike info criterion | 10.938 | |
Sum squared resid | 84191.34 | Schwarz criterion | 11.08453 | |
Log likelihood | -151.8513 | Hannan-Quinn criter. | 11.01847 | |
F-statistic | 152.9322 | Durbin-Watson stat | 1.212781 |
Prob(F-statistic) | 0.000000 | |||
三、检验模型的异方差
(一) 图形法
1. 相关关系图
X Y 相关关系图
2. 残差图形
生成残差平方序列,做与解释变量 X 的散点图如下。
与 X 散点图
3. 判断
由图可以看出,残差平方 对解释变量 X 的散点图主要分布在图形中的下三角部分,大致看出残差平方 随 X 的变动呈增大的趋势,因此,模型很可能存在异方差。但是否确实存在异方差还应通过更进一步的检验。
(二) Goldfeld-Quanadt检验
1. 排序
使用 Sort X 命令对解释变量 X 进行排序。
2. 构造子样本区间,建立回归模型
样本容量 n=28,去掉中间 c=8 个样本值,得到两个样本区间 1~10、19~28的两组样本值。
1~10区间回归估计
Dependent Variable: Y | ||||
Method: Least Squares | ||||
Date: 06/01/16 Time: 20:35 | ||||
Sample: 1 10 | ||||
Included observations: 10 | ||||
Variable | Coefficient | Std. Error | t-Statistic | Prob. |
C | 15.766 | 14.82022 | 1.063727 | 0.3185 |
X | 0.0854 | 0.019182 | 4.477937 | 0.0021 |
R-squared | 0.714814 | Mean dependent var | 77.000 | |
Adjusted R-squared | 0.679166 | S.D. dependent var | 31.70225 | |
S.E. of regression | 17.95685 | Akaike info criterion | 8.790677 | |
Sum squared resid | 2579.587 | Schwarz criterion | 8.851194 | |
Log likelihood | -41.95338 | Hannan-Quinn criter. | 8.7242 | |
F-statistic | 20.05192 | Durbin-Watson stat | 2.280129 |
Prob(F-statistic) | 0.002061 | |||
Dependent Variable: Y | ||||
Method: Least Squares | ||||
Date: 06/01/16 Time: 20:36 | ||||
Sample: 19 28 | ||||
Included observations: 10 | ||||
Variable | Coefficient | Std. Error | t-Statistic | Prob. |
C | -11.99687 | 138.62 | -0.086517 | 0.9332 |
X | 0.110552 | 0.039367 | 2.808209 | 0.0229 |
R-squared | 0.4913 | Mean dependent var | 369.2440 | |
Adjusted R-squared | 0.433465 | S.D. dependent var | 118.6175 | |
S.E. of regression | .28163 | Akaike info criterion | 11.99833 | |
Sum squared resid | 63769.67 | Schwarz criterion | 12.05884 | |
Log likelihood | -57.99163 | Hannan-Quinn criter. | 11.93194 | |
F-statistic | 7.886037 | Durbin-Watson stat | 2.4267 |
Prob(F-statistic) | 0.022906 | |||
对样本 1~10回归分析
对样本 19~28 回归分析
4. 判断
取显著性水平 ,子样本个数为 10,变量个数为 2,因此子样本的残差平方和的自由度为 8,查 F 分布表得
所以拒绝原假设,表明模型确实存在异方差性。
(三) White检验
对前文参数检验的结果进行 White 检验,结果如下图
Heteroskedasticity Test: White | ||||
F-statistic | 3.607090 | Prob. F(2,25) | 0.0420 | |
Obs*R-squared | 6.270439 | Prob. Chi-Square(2) | 0.0435 | |
Scaled explained SS | 7.630696 | Prob. Chi-Square(2) | 0.0220 | |
Test Equation: | ||||
Dependent Variable: RESID^2 | ||||
Method: Least Squares | ||||
Date: 06/01/16 Time: 20:38 | ||||
Sample: 1 28 | ||||
Included observations: 28 | ||||
Variable | Coefficient | Std. Error | t-Statistic | Prob. |
C | -3279.669 | 2857.119 | -1.1474 | 0.2619 |
X^2 | -0.000871 | 0.000653 | -1.334033 | 0.1942 |
X | 5.670687 | 3.109366 | 1.823744 | 0.0802 |
R-squared | 0.223944 | Mean dependent var | 3006.833 | |
Adjusted R-squared | 0.161860 | S.D. dependent var | 5144.454 | |
S.E. of regression | 4709.748 | Akaike info criterion | 19.85361 | |
Sum squared resid | 5.55E+08 | Schwarz criterion | 19.99635 | |
Log likelihood | -274.9506 | Hannan-Quinn criter. | 19.725 | |
F-statistic | 3.607090 | Durbin-Watson stat | 2.5702 | |
Prob(F-statistic) | 0.042040 | |||
四、异方差的修正(加权最小二乘法)
1.权数
将权数分别设置为
2. 最小二乘估计
在 Eviews 命令窗口输入
得到如下结果
Dependent Variable: Y | ||||
Method: Least Squares | ||||
Date: 06/01/16 Time: 21:39 | ||||
Sample: 1 28 | ||||
Included observations: 28 | ||||
Weighting series: W1 | ||||
Weight type: Inverse standard deviation (EViews default scaling) | ||||
Variable | Coefficient | Std. Error | t-Statistic | Prob. |
C | 5.988351 | 6.403691 | 0.935141 | 0.3583 |
X | 0.108605 | 0.008156 | 13.31659 | 0.0000 |
Weighted Statistics | ||||
R-squared | 0.872130 | Mean dependent var | 123.4049 |
Adjusted R-squared | 0.867212 | S.D. dependent var | 31.99804 | |
S.E. of regression | 32.07267 | Akaike info criterion | 9.842635 | |
Sum squared resid | 26745.07 | Schwarz criterion | 9.937792 | |
Log likelihood | -135.7969 | Hannan-Quinn criter. | 9.871726 | |
F-statistic | 177.3317 | Durbin-Watson stat | 2.386165 | |
Prob(F-statistic) | 0.000000 | Weighted mean dep. | 67.92073 | |
Unweighted Statistics | ||||
R-squared | 0.853094 | Mean dependent var | 213.4639 | |
Adjusted R-squared | 0.847443 | S.D. dependent var | 146.4905 | |
S.E. of regression | 57.21696 | Sum squared resid | 85118.31 | |
Durbin-Watson stat | 2.472027 | |||
Dependent Variable: Y | ||||
Method: Least Squares | ||||
Date: 06/01/16 Time: 21:46 | ||||
Sample: 1 28 | ||||
Included observations: 28 | ||||
Weighting series: W2 | ||||
Weight type: Inverse standard deviation (EViews default scaling) | ||||
Variable | Coefficient | Std. Error | t-Statistic | Prob. |
C | 6.497148 | 3.486625 | 1.863449 | 0.0737 |
X | 0.1060 | 0.010991 | 9.724824 | 0.0000 |
Weighted Statistics | ||||
R-squared | 0.784362 | Mean dependent var | 67.92073 |
Adjusted R-squared | 0.776068 | S.D. dependent var | 75.51949 | |
S.E. of regression | 21.39500 | Akaike info criterion | 9.032941 | |
Sum squared resid | 11901.39 | Schwarz criterion | 9.128098 | |
Log likelihood | -124.4612 | Hannan-Quinn criter. | 9.062031 | |
F-statistic | 94.57221 | Durbin-Watson stat | 2.826376 | |
Prob(F-statistic) | 0.000000 | Weighted mean dep. | 36.45271 | |
Unweighted Statistics | ||||
R-squared | 0.854180 | Mean dependent var | 213.4639 | |
Adjusted R-squared | 0.848571 | S.D. dependent var | 146.4905 | |
S.E. of regression | 57.00507 | Sum squared resid | 844.02 | |
Durbin-Watson stat | 2.41 | |||
Dependent Variable: Y | ||||
Method: Least Squares | ||||
Date: 06/01/16 Time: 21:48 | ||||
Sample: 1 28 | ||||
Included observations: 28 | ||||
Weighting series: W3 | ||||
Weight type: Inverse standard deviation (EViews default scaling) | ||||
Variable | Coefficient | Std. Error | t-Statistic | Prob. |
C | 8.639271 | 11.18768 | 0.772213 | 0.4470 |
X | 0.106153 | 0.007746 | 13.70430 | 0.0000 |
Weighted Statistics | ||||
R-squared | 0.878396 | Mean dependent var | 165.8409 |
Adjusted R-squared | 0.873718 | S.D. dependent var | 67.13183 | |
S.E. of regression | 42.63779 | Akaike info criterion | 10.41211 | |
Sum squared resid | 47267.52 | Schwarz criterion | 10.50727 | |
Log likelihood | -143.7695 | Hannan-Quinn criter. | 10.44120 | |
F-statistic | 187.8079 | Durbin-Watson stat | 2.423771 | |
Prob(F-statistic) | 0.000000 | Weighted mean dep. | 123.4049 | |
Unweighted Statistics | ||||
R-squared | 0.854451 | Mean dependent var | 213.4639 | |
Adjusted R-squared | 0.848853 | S.D. dependent var | 146.4905 | |
S.E. of regression | 56.95205 | Sum squared resid | 84331.95 | |
Durbin-Watson stat | 2.493962 | |||
3. 判断
由上述三个结果可以看出,W1 的 t 检验均显著,F 检验也显著,即对异方差的修正效果最好。选择以 W1 为权数建立的回归模型为
4. 对所估计的模型再次进行 White 检验,观察异方差调整情况
Heteroskedasticity Test: White | ||||
F-statistic | 0.555565 | Prob. F(2,25) | 0.5807 | |
Obs*R-squared | 1.191508 | Prob. Chi-Square(2) | 0.5511 | |
Scaled explained SS | 1.227886 | Prob. Chi-Square(2) | 0.5412 | |
Test Equation: | ||||
Dependent Variable: WGT_RESID^2 | ||||
Method: Least Squares | ||||
Date: 06/01/16 Time: 22:21 | ||||
Sample: 1 28 | ||||
Included observations: 28 | ||||
Collinear test regressors dropped from specification | ||||
Variable | Coefficient | Std. Error | t-Statistic | Prob. |
C | 431.5468 | 622.9142 | 0.692787 | 0.4948 |
X*WGT^2 | 0.841038 | 0.817049 | 1.029360 | 0.3132 |
WGT^2 | -203.4092 | 194.7639 | -1.0443 | 0.3063 |
R-squared | 0.042554 | Mean dependent var | 955.1810 | |
Adjusted R-squared | -0.034042 | S.D. dependent var | 1503.879 | |
S.E. of regression | 1529.262 | Akaike info criterion | 17.60392 | |
Sum squared resid | 58466086 | Schwarz criterion | 17.74665 | |
Log likelihood | -243.4548 | Hannan-Quinn criter. | 17.755 | |
F-statistic | 0.555565 | Durbin-Watson stat | 2.237493 | |
Prob(F-statistic) | 0.580670 | |||