Why no value for Adjusted R-squared?

[Greentea]

I have some balanced panel data and I ran a 2-step GMM estimation. My equation is: delta D i,t = alpha i,t + beta i,t * Xi ,j,t + error term. 1) Why after I put data into Eviews, the estimation automatically became: delta D i,t = alpha i,t + delta D(-1) i,t + beta i,t * X i,j,t + error term? That is, why Eviews add a lag 1 of the dependent variable into the equation? 2) When I got the results, I noticed there was no adjusted R-squared value available for the 2-step GMM estimation. Only mean dependent var, S.E. of regression, J-statistic, S.D. dependent var, sum squared resid and instrument rank are reported. Why?

[amkh8857]

I have the same question.
why R2 and R2-adjusted are not reported on GMM estimation with 1st difference? See below the example!

Dependent Variable: DV
Method: Panel Generalized Method of Moments
Transformation: First Differences
Date: 10/30/15 Time: 15:03
Sample (adjusted): 2001 2012
Periods included: 12
Cross-sections included: 1204
Total panel (unbalanced) observations: 12847
Difference specification instrument weighting matrix
White period standard errors & covariance (no d.f. correction)
Instrument specification: @DYN(LEV_GROWTH_STAR,-3)
@LEV(@SYSPER)
Constant added to instrument list

Variable Coefficient Std. Error t-Statistic Prob.

DV(-1) -0.138553 0.051476 -2.691603 0.0071
INVA1 0.052257 0.058489 0.893457 0.3716
INVA2 -0.042169 0.057309 -0.735830 0.4618
INVA3 -0.076944 0.074672 -1.030426 0.3028
INVA4 -0.000649 0.000833 -0.779105 0.4359
INVA5 0.308433 0.264533 1.165953 0.2437
INVA6 -0.063729 0.098692 -0.645740 0.5185
INVA7 0.006424 0.023870 0.269142 0.7878
INVA8 -0.041102 0.058377 -0.704070 0.4814
INVA9 0.082715 0.092578 0.893470 0.3716
INVA10 0.498968 0.578899 0.861927 0.3887
INVA11 -0.047363 0.069461 -0.681863 0.4953
@LEV(@ISPERIOD("2001")) -0.020691 0.021840 -0.947374 0.3435
@LEV(@ISPERIOD("2002")) 0.112814 0.116784 0.966001 0.3341
@LEV(@ISPERIOD("2003")) -0.095806 0.103332 -0.927170 0.3539
@LEV(@ISPERIOD("2004")) -0.013437 0.030480 -0.440860 0.6593
@LEV(@ISPERIOD("2005")) -0.018035 0.018129 -0.994815 0.3198
@LEV(@ISPERIOD("2006")) 0.001785 0.023917 0.074624 0.9405
@LEV(@ISPERIOD("2007")) -0.025661 0.031064 -0.826061 0.4088
@LEV(@ISPERIOD("2008")) -0.008233 0.011592 -0.710236 0.4776
@LEV(@ISPERIOD("2009")) -0.017561 0.017873 -0.982532 0.3259
@LEV(@ISPERIOD("2010")) -0.003029 0.009190 -0.329638 0.7417
@LEV(@ISPERIOD("2011")) 0.006330 0.015510 0.408142 0.6832
@LEV(@ISPERIOD("2012")) -0.015465 0.022188 -0.697015 0.4858

Effects Specification

Cross-section fixed (first differences)
Period fixed (dummy variables)

Mean dependent var -7.37E-05 S.D. dependent var 1.581541
S.E. of regression 1.497387 Sum squared resid 28751.34
J-statistic 1.427532 Instrument rank 78
Prob(J-statistic) 1.000000