[回归结果如下]. xtreg FinLevel_1 did Age ROA Size Lev i.year,fe vce(cluster id)
note: 2021.year omitted because of collinearity.
Fixed-effects (within) regression Number of obs = 11,555
Group variable: id Number of groups = 1,692
R-squared: Obs per group:
Within = 0.0244 min = 5
Between = 0.0584 avg = 6.8
Overall = 0.0472 max = 7
F(10,1691) = 8.41
corr(u_i, Xb) = -0.0696 Prob > F = 0.0000
(Std. err. adjusted for 1,692 clusters in id)
------------------------------------------------------------------------------
| Robust
FinLevel_1 | Coefficient std. err. t P>|t| [95% conf. interval]
-------------+----------------------------------------------------------------
did | 1.338135 .3652625 3.66 0.000 .6217214 2.054549
Age | .2924484 .0754649 3.88 0.000 .1444341 .4404628
ROA | -2.369897 1.316127 -1.80 0.072 -4.951307 .2115126
Size | -1.151889 .4644059 -2.48 0.013 -2.06276 -.2410181
Lev | -3.090421 1.480967 -2.09 0.037 -5.995142 -.1857003
|
year |
2016 | .2668695 .1224691 2.18 0.029 .0266626 .5070764
2017 | .2532953 .1507772 1.68 0.093 -.0424343 .5490249
2018 | -.7092419 .1868651 -3.80 0.000 -1.075753 -.3427307
2019 | .1548358 .1756203 0.88 0.378 -.1896202 .4992918
2020 | .1090393 .1235827 0.88 0.378 -.1333518 .3514304
2021 | 0 (omitted)
|
_cons | 29.11176 9.705885 3.00 0.003 10.07495 48.14857
-------------+----------------------------------------------------------------
sigma_u | 7.3565476
sigma_e | 5.8303288
rho | .61420786 (fraction of variance due to u_i)
------------------------------------------------------------------------------
. reghdfe FinLevel_1 did Age ROA Size Lev,absorb(id year) vce(cluster id)
(MWFE estimator converged in 4 iterations)
note: Age is probably collinear with the fixed effects (all partialled-out values are close to zero; tol = 1.0e-09
> )
HDFE Linear regression Number of obs = 11,555
Absorbing 2 HDFE groups F( 4, 1691) = 7.70
Statistics robust to heteroskedasticity Prob > F = 0.0000
R-squared = 0.6674
Adj R-squared = 0.6099
Within R-sq. = 0.0107
Number of clusters (id) = 1,692 Root MSE = 5.8303
(Std. err. adjusted for 1,692 clusters in id)
------------------------------------------------------------------------------
| Robust
FinLevel_1 | Coefficient std. err. t P>|t| [95% conf. interval]
-------------+----------------------------------------------------------------
did | 1.338135 .3652625 3.66 0.000 .6217214 2.054549
Age | 0 (omitted)
ROA | -2.369897 1.316127 -1.80 0.072 -4.951307 .2115126
Size | -1.151889 .4644059 -2.48 0.013 -2.06276 -.2410181
Lev | -3.090421 1.480967 -2.09 0.037 -5.995142 -.1857003
_cons | 32.95668 10.33748 3.19 0.001 12.68108 53.23228
------------------------------------------------------------------------------
Absorbed degrees of freedom:
-----------------------------------------------------+
Absorbed FE | Categories - Redundant = Num. Coefs |
-------------+---------------------------------------|
id | 1692 1692 0 *|
year | 7 1 6 |
-----------------------------------------------------+
* = FE nested within cluster; treated as redundant for DoF computation
这两个回归不应该控制的都是个体+时间的双向固定效应吗~为什么第二个会说Age存在共线性~球球各位大佬解释~