面板数据中有31个省份2000至2012年的数据,命令:xi:reg lnincome lnmarket lngdpper lnpunished lnarea i.account if province==10
回归结果是:
i.account _Iaccount_0-1 (naturally coded; _Iaccount_0 omitted)
Source | SS df MS Number of obs = 13
-------------+------------------------------ F( 5, 7) = 279.57
Model | 18.1940877 5 3.63881755 Prob > F = 0.0000
Residual | .0911091 7 .013015586 R-squared = 0.9950
-------------+------------------------------ Adj R-squared = 0.9915
Total | 18.2851968 12 1.5237664 Root MSE = .11409
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lnincome | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
lnmarket | -1.400194 .300593 -4.66 0.002 -2.110984 -.6894046
lngdpper | .9737786 .1575121 6.18 0.000 .6013216 1.346236
lnpunished | -.9481823 .2221391 -4.27 0.004 -1.473458 -.4229067
lnarea | 1.578381 .1033646 15.27 0.000 1.333963 1.8228
_Iaccount_1 | -.40596 .1430357 -2.84 0.025 -.7441857 -.0677343
_cons | -10.11132 1.393478 -7.26 0.000 -13.40637 -6.816268
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命令:
keep if province==10
(390 observations deleted)
xi:reg lnincome lnmarket lngdpper lnpunished lnarea i.account
回归结果却是:
Source | SS df MS Number of obs = 13
-------------+------------------------------ F( 5, 7) = 369.85
Model | 16.3415181 5 3.26830363 Prob > F = 0.0000
Residual | .061857048 7 .008836721 R-squared = 0.9962
-------------+------------------------------ Adj R-squared = 0.9935
Total | 16.4033752 12 1.36694793 Root MSE = .094
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lnincome | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
lnmarket | .2154888 .2621472 0.82 0.438 -.4043908 .8353684
lngdpper | .7403651 .2093011 3.54 0.010 .2454468 1.235283
lnpunished | -.2252297 .2068608 -1.09 0.312 -.7143777 .2639183
lnarea | .9215687 .1070127 8.61 0.000 .668524 1.174613
_Iaccount_1 | .4695522 .1297205 3.62 0.009 .162812 .7762925
_cons | -.5963693 1.850769 -0.32 0.757 -4.972742 3.780004
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为什么差距这么大呢,是面板数据处理过程中做了什么设定么?求大神解释下。


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