[Stata Program]
input id ability social contrib receive ach
161 .740000 1.000000 1.000000 2.333333 1.000000
164 .780000 1.000000 .000000 2.200000 .960000
159 .670000 1.000000 1.000000 2.500000 .950000
196 .740000 2.000000 2.000000 1.428571 .930000
189 .770000 3.000000 1.000000 1.666667 .920000
191 .800000 1.000000 6.000000 1.666667 .915000
334 .870000 9.000000 15.00000 .000000 .915000
173 .810000 1.000000 3.000000 1.250000 .910000
131 .750000 1.000000 8.000000 1.571429 .890000
214 .700000 3.000000 3.000000 3.000000 .885000
180 .760000 .000000 3.000000 1.000000 .880000
152 .800000 3.000000 7.000000 .666667 .875000
336 .670000 10.00000 5.000000 1.300000 .860000
188 .670000 3.000000 .000000 1.333333 .850000
337 .670000 9.000000 8.000000 -.400000 .850000
172 .650000 5.000000 2.000000 1.545455 .850000
186 .830000 3.000000 2.000000 .166667 .840000
209 .870000 5.000000 3.000000 1.000000 .833810
201 .780000 15.00000 6.000000 .000000 .830000
133 .680000 2.000000 6.000000 .578947 .825000
210 .690000 3.000000 .000000 1.500000 .810000
303 .880000 7.000000 12.00000 .285714 .935000
167 .730000 1.000000 7.000000 1.333333 .930000
333 .760000 1.000000 3.000000 1.142857 .890000
144 .740000 8.000000 3.000000 1.000000 .885000
207 .860000 .000000 6.000000 .900000 .885000
255 .700000 .000000 8.000000 1.428571 .885000
175 .640000 .000000 4.000000 1.571429 .860000
143 .730000 11.00000 4.000000 1.500000 .860000
347 .920000 .000000 7.000000 1.250000 .850000
241 .670000 .000000 10.00000 .687500 .840000
135 .790000 7.000000 8.000000 1.000000 .835000
244 .650000 .000000 4.000000 1.000000 .835000
262 .900000 .000000 8.000000 .333333 .820000
297 .750000 .000000 3.000000 .600000 .820000
341 .660000 .000000 5.000000 2.000000 .820000
305 .620000 .000000 3.000000 1.625000 .815000
332 .640000 .000000 3.000000 1.000000 .815000
193 .720000 4.000000 17.00000 1.428571 .770000
148 .800000 6.000000 8.000000 .666667 .740000
274 .670000 18.00000 10.00000 .000000 .740000
308 .670000 .000000 9.000000 1.000000 .735000
156 .790000 4.000000 14.00000 .076923 .725000
136 .690000 5.000000 16.00000 .857143 .700000
272 .730000 3.000000 9.000000 .800000 .700000
216 .690000 14.00000 27.00000 .363636 .680000
247 .790000 .000000 8.000000 .250000 .675000
150 .650000 5.000000 4.000000 .625000 .670000
220 .700000 18.00000 7.000000 .428571 .670000
259 .886667 .000000 8.000000 .666667 .670000
228 .670000 13.00000 7.000000 .600000 .645000
357 .590000 8.000000 14.00000 .421053 .645000
383 .610000 3.000000 15.00000 .294118 .625000
232 .700000 1.000000 19.00000 .800000 .600000
275 .590000 .000000 9.000000 .666667 .600000
338 .630000 12.00000 21.00000 .000000 .465000
end
summarize ach ability receive contrib social
correlate ach ability receive contrib social
regress ach ability
sw regress ach ability receive contrib social, beta pe(.05) lockterm1
test receive contrib
regress ach ability receive contrib social
vif
test social
[Stata Output]
summarize ach ability receive contrib social
Variable | Obs Mean Std. Dev. Min Max
-------------+-----------------------------------------------------
ach | 56 .8073895 .1101722 .465 1
ability | 56 .7306548 .0826076 .59 .92
receive | 56 .9805444 .688402 -.4 3
contrib | 56 7.178571 5.608783 0 27
social | 56 4.107143 4.867998 0 18
correlate ach ability receive contrib social
(obs=56)
| ach ability receive contrib social
-------------+---------------------------------------------
ach | 1.0000
ability | 0.3760 1.0000
receive | 0.5322 -0.1067 1.0000
contrib | -0.6205 -0.0879 -0.5246 1.0000
social | -0.3068 -0.1230 -0.4416 0.3429 1.0000
regress ach ability
Source | SS df MS Number of obs = 56
-------------+------------------------------ F( 1, 54) = 8.89
Model | .094366369 1 .094366369 Prob > F = 0.0043
Residual | .573218887 54 .010615165 R-squared = 0.1414
-------------+------------------------------ Adj R-squared = 0.1255
Total | .667585256 55 .012137914 Root MSE = .10303
------------------------------------------------------------------------------
ach | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
ability | .5014267 .1681753 2.98 0.004 .1642555 .8385978
_cons | .4410197 .123647 3.57 0.001 .1931224 .688917
------------------------------------------------------------------------------
sw regress ach ability receive contrib social, beta pe(.05) lockterm1
begin with term 1 model
p = 0.0000 < 0.0500 adding contrib
p = 0.0012 < 0.0500 adding receive
Source | SS df MS Number of obs = 56
-------------+------------------------------ F( 3, 52) = 24.21
Model | .389060023 3 .129686674 Prob > F = 0.0000
Residual | .278525233 52 .005356254 R-squared = 0.5828
-------------+------------------------------ Adj R-squared = 0.5587
Total | .667585256 55 .012137914 Root MSE = .07319
------------------------------------------------------------------------------
ach | Coef. Std. Err. t P>|t| Beta
-------------+----------------------------------------------------------------
ability | .5070472 .1219206 4.16 0.000 .380186
contrib | -.0077676 .0020971 -3.70 0.000 -.3954446
receive | .0584736 .0171179 3.42 0.001 .3653677
_cons | .4353376 .0990279 4.40 0.000 .
------------------------------------------------------------------------------
test receive contrib
( 1) receive = 0.0
( 2) contrib = 0.0
F( 2, 52) = 27.51
Prob > F = 0.0000
regress ach ability receive contrib social
Source | SS df MS Number of obs = 56
-------------+------------------------------ F( 4, 51) = 17.94
Model | .39024775 4 .097561937 Prob > F = 0.0000
Residual | .277337506 51 .00543799 R-squared = 0.5846
-------------+------------------------------ Adj R-squared = 0.5520
Total | .667585256 55 .012137914 Root MSE = .07374
------------------------------------------------------------------------------
ach | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
ability | .516964 .1246665 4.15 0.000 .2666856 .7672424
receive | .0615114 .0184322 3.34 0.002 .0245073 .0985156
contrib | -.007884 .0021277 -3.71 0.000 -.0121555 -.0036125
social | .0010914 .0023353 0.47 0.642 -.0035969 .0057796
_cons | .4214662 .1041016 4.05 0.000 .2124735 .6304588
------------------------------------------------------------------------------
vif
Variable | VIF 1/VIF
-------------+----------------------
receive | 1.63 0.614097
contrib | 1.44 0.694261
social | 1.31 0.765071
ability | 1.07 0.932259
-------------+----------------------
Mean VIF | 1.36
test social
( 1) social = 0.0
F( 1, 51) = 0.22
Prob > F = 0.6422