Hi
I am having problems with -xtivreg- .
I run the following regression:
xi:xtivreg jbhrs age agesq (wage=jbpen), i(pid) fe
However, the within group R-squared is missing and I cannot figure out why. can anyone give me a clue as to what might be the problem?
Fixed-effects (within) IV regression Number of obs = 10554
Group variable: pid Number of groups = 4814
R-sq: within = . Obs per group: min = 1
between = 0.0040 avg = 2.2
overall = 0.0006 max = 5
Wald chi2(3) = 691475.43
corr(u_i, Xb) = -0.1610 Prob > chi2 = 0.0000
------------------------------------------------------------------------------
jbhrs | Coef. Std. Err. z P>|z| [95% Conf. Interval]
-------------+----------------------------------------------------------------
wage | .1258948 .3909938 0.32 0.747 -.6404389 .8922286
age | .492656 .4087827 1.21 0.228 -.3085433 1.293855
agesq | -.6923237 .2895229 -2.39 0.017 -1.259778 -.1248692
_cons | 30.46965 7.452747 4.09 0.000 15.86253 45.07676
-------------+----------------------------------------------------------------
sigma_u | 7.1165299
sigma_e | 4.8714714
rho | .68092987 (fraction of variance due to u_i)
------------------------------------------------------------------------------
F test that all u_i=0: F(4813,5737) = 3.54 Prob > F = 0.0000
------------------------------------------------------------------------------
Instrumented: wage
Instruments: age agesq jbpen
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
