. regress ltradeab lgdpab lrpopab ldistab allied mindem if nyears>=20 Source | SS df MS Number of obs = 93924 ---------+------------------------------ F( 5, 93918) =10569.17 Model | 925287.222 5 185057.444 Prob > F = 0.0000 Residual | 1644426.85 93918 17.5091766 R-squared = 0.3601 ---------+------------------------------ Adj R-squared = 0.3600 Total | 2569714.07 93923 27.3597955 Root MSE = 4.1844 ------------------------------------------------------------------------------ ltradeab | Coef. Std. Err. t P>|t| [95% Conf. Interval] ---------+-------------------------------------------------------------------- lgdpab | 1.182442 .0075438 156.744 0.000 1.167656 1.197228 lrpopab | -.3859683 .0097211 -39.704 0.000 -.4050216 -.366915 ldistab | -1.341865 .0176361 -76.086 0.000 -1.376432 -1.307299 allied | -.7445702 .0421351 -17.671 0.000 -.8271545 -.6619859 mindem | .0753349 .0020938 35.981 0.000 .0712311 .0794386 _cons | -17.33061 .2647488 -65.461 0.000 -17.84952 -16.81171 ------------------------------------------------------------------------------ . iis dyadid . tis year . xtreg ltradeab lgdpab lrpopab ldistab allied mindem if nyears>=20, fe Fixed-effects (within) regression Number of obs = 93924 Group variable (i) : dyadid Number of groups = 3079 R-sq: within = 0.2286 Obs per group: min = 20 between = 0.2127 avg = 30.5 overall = 0.2051 max = 42 F(4,90841) = 6729.00 corr(u_i, Xb) = -0.3726 Prob > F = 0.0000 ------------------------------------------------------------------------------ ltradeab | Coef. Std. Err. t P>|t| [95% Conf. Interval] ---------+-------------------------------------------------------------------- lgdpab | .8096007 .0154861 52.279 0.000 .7792481 .8399532 lrpopab | .7518906 .081798 9.192 0.000 .5915672 .912214 ldistab | (dropped) allied | .7768308 .1356515 5.727 0.000 .5109552 1.042706 mindem | -.0394317 .0029373 -13.425 0.000 -.0451887 -.0336746 _cons | -47.99424 1.999253 -24.006 0.000 -51.91275 -44.07572 ------------------------------------------------------------------------------ sigma_u | 3.8469425 sigma_e | 3.1691435 rho | .59571315 (fraction of variance due to u_i) ------------------------------------------------------------------------------ F test that all u_i=0: F(3078,90841) = 23.68 Prob > F = 0.0000 . xtreg ltradeab lgdpab lrpopab ldistab allied mindem if nyears>=20, re Random-effects GLS regression Number of obs = 93924 Group variable (i) : dyadid Number of groups = 3079 R-sq: within = 0.2269 Obs per group: min = 20 between = 0.4138 avg = 30.5 overall = 0.3305 max = 42 Random effects u_i ~ Gaussian Wald chi2(5) = 28883.16 corr(u_i, X) = 0 (assumed) Prob > chi2 = 0.0000 ------------------------------------------------------------------------------ ltradeab | Coef. Std. Err. z P>|z| [95% Conf. Interval] ---------+-------------------------------------------------------------------- lgdpab | .9799895 .008056 121.647 0.000 .9642 .995779 lrpopab | -.1616708 .0266315 -6.071 0.000 -.2138676 -.1094739 ldistab | -1.250704 .0635867 -19.669 0.000 -1.375332 -1.126077 allied | .0125228 .1053301 0.119 0.905 -.1939203 .218966 mindem | -.0240615 .0028122 -8.556 0.000 -.0295732 -.0185497 _cons | -16.4364 .7983955 -20.587 0.000 -18.00122 -14.87157 ---------+-------------------------------------------------------------------- sigma_u | 2.7897647 sigma_e | 3.1691435 rho | .43659119 (fraction of variance due to u_i) ------------------------------------------------------------------------------ . xttest0 Breusch and Pagan Lagrangian multiplier test for random effects: ltradeab[dyadid,t] = Xb + u[dyadid] + e[dyadid,t] Estimated results: Var sd = sqrt(Var) ---------+----------------------------- ltradeab | 27.3598 5.230659 e | 10.04347 3.1691435 u | 7.782787 2.7897647 Test: Var(u) = 0 chi2(1) = 186889.80 Prob>chi2 = 0.0000 . xthaus Hausman specification test ---- Coefficients ---- | Fixed Random ltradeab | Effects Effects Difference ---------+----------------------------------------- lgdpab | .8096007 .9799895 -.1703888 lrpopab | .7518906 -.1616708 .9135614 allied | .7768308 .0125228 .764308 mindem | -.0394317 -.0240615 -.0153702 Test: Ho: difference in coefficients not systematic chi2( 4) = (b-B)'[S^(-1)](b-B), S = (S_fe - S_re) = 869.97 Prob>chi2 = 0.0000 . regress ltradeab lgdpab lrpopab ldistab allied mindem ltrade1 if nyears>=20 Source | SS df MS Number of obs = 88946 ---------+------------------------------ F( 6, 88939) =39632.55 Model | 1656959.50 6 276159.916 Prob > F = 0.0000 Residual | 619727.702 88939 6.96800844 R-squared = 0.7278 ---------+------------------------------ Adj R-squared = 0.7278 Total | 2276687.20 88945 25.5965732 Root MSE = 2.6397 ------------------------------------------------------------------------------ ltradeab | Coef. Std. Err. t P>|t| [95% Conf. Interval] ---------+-------------------------------------------------------------------- lgdpab | .2503381 .0055742 44.910 0.000 .2394128 .2612634 lrpopab | -.0590858 .0063982 -9.235 0.000 -.0716261 -.0465455 ldistab | -.3284747 .0117772 -27.891 0.000 -.3515579 -.3053914 allied | -.2465617 .0273329 -9.021 0.000 -.3001339 -.1929895 mindem | .0220639 .0013678 16.131 0.000 .019383 .0247448 ltrade1 | .7358783 .0021154 347.865 0.000 .7317321 .7400245 _cons | -3.045513 .1768478 -17.221 0.000 -3.392133 -2.698893 ------------------------------------------------------------------------------ . xtreg ltradeab lgdpab lrpopab ldistab allied mindem ltrade1 if nyears>=20, fe Fixed-effects (within) regression Number of obs = 88946 Group variable (i) : dyadid Number of groups = 3079 R-sq: within = 0.4604 Obs per group: min = 15 between = 0.8940 avg = 28.9 overall = 0.6920 max = 41 F(5,85862) = 14649.22 corr(u_i, Xb) = 0.4247 Prob > F = 0.0000 ------------------------------------------------------------------------------ ltradeab | Coef. Std. Err. t P>|t| [95% Conf. Interval] ---------+-------------------------------------------------------------------- lgdpab | .3416602 .0129523 26.378 0.000 .3162738 .3670467 lrpopab | .143265 .0681072 2.104 0.035 .0097755 .2767544 ldistab | (dropped) allied | .4192872 .120994 3.465 0.001 .1821399 .6564344 mindem | -.0091264 .002429 -3.757 0.000 -.0138872 -.0043656 ltrade1 | .5334145 .0026973 197.757 0.000 .5281277 .5387012 _cons | -13.74517 1.676376 -8.199 0.000 -17.03085 -10.45949 ------------------------------------------------------------------------------ sigma_u | 1.58733 sigma_e | 2.4956935 rho | .28801862 (fraction of variance due to u_i) ------------------------------------------------------------------------------ F test that all u_i=0: F(3078,85862) = 4.43 Prob > F = 0.0000 . xtreg ltradeab lgdpab lrpopab ldistab allied mindem ltrade1 if nyears>=20, re Random-effects GLS regression Number of obs = 88946 Group variable (i) : dyadid Number of groups = 3079 R-sq: within = 0.4533 Obs per group: min = 15 between = 0.9812 avg = 28.9 overall = 0.7278 max = 41 Random effects u_i ~ Gaussian Wald chi2(6) = 237795.28 corr(u_i, X) = 0 (assumed) Prob > chi2 = 0.0000 ------------------------------------------------------------------------------ ltradeab | Coef. Std. Err. z P>|z| [95% Conf. Interval] ---------+-------------------------------------------------------------------- lgdpab | .2503381 .0055742 44.910 0.000 .2394129 .2612633 lrpopab | -.0590858 .0063982 -9.235 0.000 -.0716259 -.0465456 ldistab | -.3284747 .0117772 -27.891 0.000 -.3515576 -.3053918 allied | -.2465617 .0273329 -9.021 0.000 -.3001332 -.1929903 mindem | .0220639 .0013678 16.131 0.000 .019383 .0247448 ltrade1 | .7358783 .0021154 347.865 0.000 .7317322 .7400244 _cons | -3.045513 .1768478 -17.221 0.000 -3.392128 -2.698898 ---------+-------------------------------------------------------------------- sigma_u | 0 sigma_e | 2.4956935 rho | 0 (fraction of variance due to u_i) ------------------------------------------------------------------------------ . xttest0 Breusch and Pagan Lagrangian multiplier test for random effects: ltradeab[dyadid,t] = Xb + u[dyadid] + e[dyadid,t] Estimated results: Var sd = sqrt(Var) ---------+----------------------------- ltradeab | 25.59657 5.059306 e | 6.228486 2.4956935 u | 0 0 Test: Var(u) = 0 chi2(1) = 1566.17 Prob>chi2 = 0.0000 . xthaus Hausman specification test ---- Coefficients ---- | Fixed Random ltradeab | Effects Effects Difference ---------+----------------------------------------- lgdpab | .3416602 .2503381 .0913221 lrpopab | .143265 -.0590858 .2023507 allied | .4192872 -.2465617 .6658489 mindem | -.0091264 .0220639 -.0311903 ltrade1 | .5334145 .7358783 -.2024638 Test: Ho: difference in coefficients not systematic chi2( 5) = (b-B)'[S^(-1)](b-B), S = (S_fe - S_re) = 14754.01 Prob>chi2 = 0.0000 . log close