xtreg lncyjg lner lnkfd lncshl lngzsp
Random-effects GLS regression Number of obs = 156
Group variable: id Number of groups = 13
R-sq: within = 0.7923 Obs per group: min = 12
between = 0.6400 avg = 12.0
overall = 0.7484 max = 12
Wald chi2(4) = 555.20
corr(u_i, X) = 0 (assumed) Prob > chi2 = 0.0000
------------------------------------------------------------------------------
lncyjg | Coef. Std. Err. z P>|z| [95% Conf. Interval]
-------------+----------------------------------------------------------------
lner | -.3293905 .3807791 -0.87 0.387 -1.075704 .4169228
lnkfd | .0571138 .15594 0.37 0.714 -.2485231 .3627506
lncshl | .8821506 .6996323 1.26 0.207 -.4891035 2.253405
lngzsp | 2.455835 .4087916 6.01 0.000 1.654618 3.257052
_cons | -19.99817 1.463623 -13.66 0.000 -22.86681 -17.12952
-------------+----------------------------------------------------------------
sigma_u | .48286425
sigma_e | .5711602
rho | .41681346 (fraction of variance due to u_i)
------------------------------------------------------------------------------
. xtreg lncyjg lner lnkfd lncshl lngzsp,fe
Fixed-effects (within) regression Number of obs = 156
Group variable: id Number of groups = 13
R-sq: within = 0.7939 Obs per group: min = 12
between = 0.5342 avg = 12.0
overall = 0.7164 max = 12
F(4,139) = 133.82
corr(u_i, Xb) = 0.0802 Prob > F = 0.0000
------------------------------------------------------------------------------
lncyjg | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
lner | -.8064262 .4958935 -1.63 0.106 -1.786896 .1740433
lnkfd | .0347789 .1747608 0.20 0.843 -.3107544 .3803121
lncshl | 1.074469 .7556235 1.42 0.157 -.4195332 2.568471
lngzsp | 2.941188 .532916 5.52 0.000 1.887518 3.994858
_cons | -20.71514 1.553391 -13.34 0.000 -23.78647 -17.64381
-------------+----------------------------------------------------------------
sigma_u | .53546266
sigma_e | .5711602
rho | .46777544 (fraction of variance due to u_i)
------------------------------------------------------------------------------
F test that all u_i=0: F(12, 139) = 7.32 Prob > F = 0.0000
. estimates store FE
. xtreg lncyjg lner lnkfd lncshl lngzsp,re
Random-effects GLS regression Number of obs = 156
Group variable: id Number of groups = 13
R-sq: within = 0.7923 Obs per group: min = 12
between = 0.6400 avg = 12.0
overall = 0.7484 max = 12
Wald chi2(4) = 555.20
corr(u_i, X) = 0 (assumed) Prob > chi2 = 0.0000
------------------------------------------------------------------------------
lncyjg | Coef. Std. Err. z P>|z| [95% Conf. Interval]
-------------+----------------------------------------------------------------
lner | -.3293905 .3807791 -0.87 0.387 -1.075704 .4169228
lnkfd | .0571138 .15594 0.37 0.714 -.2485231 .3627506
lncshl | .8821506 .6996323 1.26 0.207 -.4891035 2.253405
lngzsp | 2.455835 .4087916 6.01 0.000 1.654618 3.257052
_cons | -19.99817 1.463623 -13.66 0.000 -22.86681 -17.12952
-------------+----------------------------------------------------------------
sigma_u | .48286425
sigma_e | .5711602
rho | .41681346 (fraction of variance due to u_i)
------------------------------------------------------------------------------
. estimates store RE
. hausman FE RE,constant sigmamore
---- Coefficients ----
| (b) (B) (b-B) sqrt(diag(V_b-V_B))
| FE RE Difference S.E.
-------------+----------------------------------------------------------------
lner | -.8064262 -.3293905 -.4770358 .3150019
lnkfd | .0347789 .0571138 -.0223349 .0775499
lncshl | 1.074469 .8821506 .1923181 .2784855
lngzsp | 2.941188 2.455835 .4853532 .3390213
_cons | -20.71514 -19.99817 -.716977 .5042159
------------------------------------------------------------------------------
b = consistent under Ho and Ha; obtained from xtreg
B = inconsistent under Ha, efficient under Ho; obtained from xtreg
Test: Ho: difference in coefficients not systematic
chi2(5) = (b-B)'[(V_b-V_B)^(-1)](b-B)
= 2.98
Prob>chi2 = 0.7028
(V_b-V_B is not positive definite)