Would it be possible for someone to outline how the two approaches I have used differ, and which is most appropriate.



xtreg ppvt_raw DISASTER disjunt juntos WORKTIME i.headedu i.gender i.region, fe
note: 2.gender omitted because of collinearity

Fixed-effects (within) regression Number of obs = 5,241
Group variable: panelid Number of groups = 1,890

R-sq: Obs per group:
within = 0.1555 min = 1
between = 0.1519 avg = 2.8
overall = 0.1355 max = 3

F(22,3329) = 27.86
corr(u_i, Xb) = -0.3568 Prob > F = 0.0000

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ppvt_raw | Coef. Std. Err. t P>|t| [95% Conf. Interval]
---------------------------------------------+----------------------------------------------------------------
DISASTER | -4.124934 1.359051 -3.04 0.002 -6.789593 -1.460275
disjunt | 1.555855 1.990849 0.78 0.435 -2.347556 5.459266
juntos | 10.4974 1.543968 6.80 0.000 7.470174 13.52462
WORKTIME | 4.015787 .2564161 15.66 0.000 3.513037 4.518536
|
headedu |
Grade 1 | -3.024054 4.894436 -0.62 0.537 -12.62046 6.572353
Grade 2 | -11.81112 4.382628 -2.69 0.007 -20.40404 -3.218205
Grade 3 | -.3126233 3.994654 -0.08 0.938 -8.144848 7.519602
Grade 4 | .8936467 4.596557 0.19 0.846 -8.118715 9.906009
Grade 5 | -3.632201 4.149429 -0.88 0.381 -11.76789 4.503488
Grade 6 | 9.45312 3.649478 2.59 0.010 2.297674 16.60857
Grade 7 | 9.480014 4.658118 2.04 0.042 .3469491 18.61308
Grade 8 | 10.84689 4.532676 2.39 0.017 1.959783 19.73401
Grade 9 | 11.9329 4.10398 2.91 0.004 3.886323 19.97948
Grade 10 | 15.02676 5.100044 2.95 0.003 5.027222 25.0263
Grade 11 | 16.61036 3.755945 4.42 0.000 9.246162 23.97455
Technical, pedagogical, CETPRO (incomplete) | 16.72069 4.644156 3.60 0.000 7.615005 25.82638
Technical, pedagogical, CETPRO (complete) | 25.04751 4.327413 5.79 0.000 16.56285 33.53217
University (incomplete) | 27.43524 5.381455 5.10 0.000 16.88394 37.98653
University (complete) | 33.93681 4.964016 6.84 0.000 24.20398 43.66964
17 | 38.95131 24.35117 1.60 0.110 -8.793468 86.6961
|
gender |
female | 0 (omitted)
|
region |
Sierra | -22.75027 2.313365 -9.83 0.000 -27.28603 -18.21451
Selva | -9.289368 3.627105 -2.56 0.010 -16.40095 -2.177788
|
_cons | 72.82197 3.692845 19.72 0.000 65.58149 80.06245
---------------------------------------------+----------------------------------------------------------------
sigma_u | 16.901904
sigma_e | 19.594292
rho | .42662758 (fraction of variance due to u_i)
--------------------------------------------------------------------------------------------------------------
F test that all u_i=0: F(1889, 3329) = 1.43 Prob > F = 0.0000



xi: regress ppvt_raw DISASTER disjunt juntos WORKTIME i.headedu i.gender i.region
i.headedu _Iheadedu_0-17 (naturally coded; _Iheadedu_0 omitted)
i.gender _Igender_1-2 (naturally coded; _Igender_1 omitted)
i.region _Iregion_31-33 (naturally coded; _Iregion_31 omitted)

Source | SS df MS Number of obs = 5,241
-------------+---------------------------------- F(23, 5217) = 58.07
Model | 590458.876 23 25672.1251 Prob > F = 0.0000
Residual | 2306419.53 5,217 442.096901 R-squared = 0.2038
-------------+---------------------------------- Adj R-squared = 0.2003
Total | 2896878.41 5,240 552.839391 Root MSE = 21.026

------------------------------------------------------------------------------
ppvt_raw | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
DISASTER | -8.214078 1.075542 -7.64 0.000 -10.32259 -6.105565
disjunt | 3.304307 1.638702 2.02 0.044 .0917642 6.516849
juntos | -3.876099 1.041407 -3.72 0.000 -5.917693 -1.834505
WORKTIME | 1.652771 .2115815 7.81 0.000 1.237983 2.067559
_Iheadedu_1 | 2.237623 2.383351 0.94 0.348 -2.434743 6.909989
_Iheadedu_2 | -1.935282 1.915909 -1.01 0.312 -5.691266 1.820702
_Iheadedu_3 | 2.919267 1.817414 1.61 0.108 -.6436249 6.482158
_Iheadedu_4 | 2.588977 2.077937 1.25 0.213 -1.48465 6.662604
_Iheadedu_5 | 1.563857 1.858906 0.84 0.400 -2.080378 5.208091
_Iheadedu_6 | 8.286911 1.573165 5.27 0.000 5.202849 11.37097
_Iheadedu_7 | 6.0136 2.233944 2.69 0.007 1.634133 10.39307
_Iheadedu_8 | 10.79432 2.025451 5.33 0.000 6.823584 14.76505
_Iheadedu_9 | 12.59025 1.853089 6.79 0.000 8.957423 16.22308
_Iheadedu_10 | 13.38254 2.366417 5.66 0.000 8.743368 18.0217
_Iheadedu_11 | 15.76536 1.541536 10.23 0.000 12.7433 18.78741
_Iheadedu_13 | 17.31192 1.992669 8.69 0.000 13.40545 21.21839
_Iheadedu_14 | 23.40903 1.798692 13.01 0.000 19.88284 26.93522
_Iheadedu_15 | 24.99694 2.366636 10.56 0.000 20.35734 29.63654
_Iheadedu_16 | 28.22627 2.105169 13.41 0.000 24.09926 32.35329
_Iheadedu_17 | 17.0119 21.09093 0.81 0.420 -24.33515 58.35895
_Igender_2 | -2.691638 .5840434 -4.61 0.000 -3.836607 -1.546668
_Iregion_32 | -6.016723 .7239521 -8.31 0.000 -7.435973 -4.597474
_Iregion_33 | -5.260057 .895482 -5.87 0.000 -7.015576 -3.504537
_cons | 73.24816 1.567087 46.74 0.000 70.17602 76.32031
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