(1)我做了一个回归,其中有一个关键的解释变量是LEV (资产负债率),但是回归结果却显示其t值非常小,有没有什么办法可以不删除掉LEV但是提高其t 值???
因为我阅读了几位学者的文献,也有LEV对于盈余管理的影响,在其回归中LEV的t值很大,该变量非常显著。但是不知道为什么我的回归中就不显著,,求大神指教~
(2)还有一个问题是,在我删除掉一些观察值后(关键样本点:既可能是杠杆样本点,也可能是残差非常大的样本点),再次回归之后有两个变量的显著性发生明显的变化,那么我应不应该删除掉这些观测值呢???
回归结果如下:
Source | SS df MS Number of obs = 15420
-------------+------------------------------ F( 9, 15410) = 218.23
Model | 68.2730629 9 7.58589588 Prob > F = 0.0000
Residual | 535.658468 15410 .034760446 R-squared = 0.1130
-------------+------------------------------ Adj R-squared = 0.1125
Total | 603.931531 15419 .039168009 Root MSE = .18644
------------------------------------------------------------------------------
RM_w | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
ln_layer | .0221527 .0037127 5.97 0.000 .0148753 .0294301
size | -.0046497 .0013156 -3.53 0.000 -.0072285 -.002071
Totalasset~r | .0226481 .0023818 9.51 0.000 .0179796 .0273166
dum_Integr~1 | -.0147124 .0039958 -3.68 0.000 -.0225446 -.0068801
dum_Big4_0~1 | -.0627389 .0069376 -9.04 0.000 -.0763375 -.0491404
dum_IEn_1 | .013456 .0033153 4.06 0.000 .0069577 .0199543
LargeHolde~e | -.0002718 .0001037 -2.62 0.009 -.000475 -.0000686
LEV | -.000428 .0002118 -2.02 0.043 -.0008432 -.0000129
ROA_w | -.8972777 .0230026 -39.01 0.000 -.9423654 -.8521899
_cons | .1057251 .0279139 3.79 0.000 .0510106 .1604396
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删除掉关键样本点之后的回归结果:
Source | SS df MS Number of obs = 14364
-------------+------------------------------ F( 9, 14354) = 287.80
Model | 51.3555208 9 5.70616898 Prob > F = 0.0000
Residual | 284.591993 14354 .019826668 R-squared = 0.1529
-------------+------------------------------ Adj R-squared = 0.1523
Total | 335.947514 14363 .023389787 Root MSE = .14081
------------------------------------------------------------------------------
RM_w | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
ln_layer | .0179648 .0029488 6.09 0.000 .0121848 .0237448
size | -.0020395 .0010514 -1.94 0.052 -.0041005 .0000214
Totalasset~r | .0268118 .002412 11.12 0.000 .0220841 .0315396
dum_Integr~1 | -.0117838 .0031679 -3.72 0.000 -.0179933 -.0055742
dum_Big4_0~1 | -.0391976 .0058295 -6.72 0.000 -.0506242 -.027771
dum_IEn_1 | .0065866 .0026071 2.53 0.012 .0014763 .0116969
LargeHolde~e | -.0000458 .0000819 -0.56 0.576 -.0002063 .0001148
LEV | .0013111 .0027958 0.47 0.639 -.004169 .0067912
ROA_w | -.9303946 .0202147 -46.03 0.000 -.970018 -.8907712
_cons | .0504948 .0223515 2.26 0.024 .006683 .0943067
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