[Stata Program]
use http://www.gseis.ucla.edu/courses/data/surg335
summarize
correlate
regress y x1 x2 x3 x4
predict p1
predict r1, residual
plot y x1
plot y x2
plot y x3
plot y x4
plot r1 x1
plot r1 x2
plot r1 x3
plot r1 x4
plot r1 p1
regress logy x1 x2 x3 x4
predict p2
predict r2, residual
plot logy x1
plot logy x2
plot logy x3
plot logy x4
plot r2 x1
plot r2 x2
plot r2 x3
plot r2 x4
plot r2 p2
[Stata Output]
summarize
Variable | Obs Mean Std. Dev. Min Max
---------+-----------------------------------------------------
case | 54 27.5 15.73213 1 54
x1 | 54 5.783333 1.603034 2.6 11.2
x2 | 54 63.24074 16.90253 8 96
x3 | 54 77.11111 21.25378 23 119
x4 | 54 2.744259 1.070356 .74 6.4
y | 54 197.1667 145.2994 34 830
logy | 54 2.206144 .2737845 1.5315 2.9191
correlate
(obs=54)
| case x1 x2 x3 x4 y logy
---------+---------------------------------------------------------------
case | 1.0000
x1 | -0.0981 1.0000
x2 | 0.0281 0.0901 1.0000
x3 | 0.1149 -0.1496 -0.0236 1.0000
x4 | 0.0616 0.5024 0.3690 0.4164 1.0000
y | -0.0085 0.3725 0.5540 0.5802 0.7223 1.0000
logy | 0.0696 0.3464 0.5929 0.6651 0.7262 0.9131 1.0000
regress y x1 x2 x3 x4
Source | SS df MS Number of obs = 54
---------+------------------------------ F( 4, 49) = 62.79
Model | 936264.538 4 234066.135 Prob > F = 0.0000
Residual | 182666.962 49 3727.89718 R-squared = 0.8367
---------+------------------------------ Adj R-squared = 0.8234
Total | 1118931.50 53 21111.9151 Root MSE = 61.057
------------------------------------------------------------------------------
y | Coef. Std. Err. t P>|t| [95% Conf. Interval]
---------+--------------------------------------------------------------------
x1 | 33.16383 7.017275 4.726 0.000 19.06209 47.26557
x2 | 4.27186 .5633845 7.582 0.000 3.139696 5.404023
x3 | 4.125738 .5111609 8.071 0.000 3.098522 5.152955
x4 | 14.09156 12.52533 1.125 0.266 -11.07902 39.26215
_cons | -621.5975 64.80043 -9.592 0.000 -751.8189 -491.3762
------------------------------------------------------------------------------
predict p1
(option xb assumed; fitted values)
predict r1, residual
plot y x1
830 +
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+----------------------------------------------------------------+
2.6 blood clotting score 11.2
plot y x2
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+----------------------------------------------------------------+
8 prognostic index 96
plot y x3
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+----------------------------------------------------------------+
23 enzyme function test 119
plot y x4
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+----------------------------------------------------------------+
.74 liver function test 6.4
plot r1 x1
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+----------------------------------------------------------------+
2.6 blood clotting score 11.2
plot r1 x2
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+----------------------------------------------------------------+
8 prognostic index 96
plot r1 x3
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+----------------------------------------------------------------+
23 enzyme function test 119
plot r1 x4
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-80.5226 + *
+----------------------------------------------------------------+
.74 liver function test 6.4
plot r1 p1
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+----------------------------------------------------------------+
-90.0293 Fitted values 524.587
regress logy x1 x2 x3 x4
Source | SS df MS Number of obs = 54
---------+------------------------------ F( 4, 49) = 431.10
Model | 3.86300182 4 .965750454 Prob > F = 0.0000
Residual | .109770615 49 .002240217 R-squared = 0.9724
---------+------------------------------ Adj R-squared = 0.9701
Total | 3.97277243 53 .07495797 Root MSE = .04733
------------------------------------------------------------------------------
logy | Coef. Std. Err. t P>|t| [95% Conf. Interval]
---------+--------------------------------------------------------------------
x1 | .0685202 .0054398 12.596 0.000 .0575885 .0794518
x2 | .0092541 .0004367 21.189 0.000 .0083765 .0101318
x3 | .0094745 .0003963 23.910 0.000 .0086782 .0102708
x4 | .0019254 .0097096 0.198 0.844 -.0175868 .0214376
_cons | .4887559 .0502332 9.730 0.000 .3878085 .5897033
------------------------------------------------------------------------------
predict p2
(option xb assumed; fitted values)
predict r2, residual
plot logy x1
2.9191 +
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1.5315 + *
+----------------------------------------------------------------+
2.6 blood clotting score 11.2
plot logy x2
2.9191 +
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1.5315 + *
+----------------------------------------------------------------+
8 prognostic index 96
plot logy x3
2.9191 +
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1.5315 + *
+----------------------------------------------------------------+
23 enzyme function test 119
plot logy x4
2.9191 +
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+----------------------------------------------------------------+
.74 liver function test 6.4
plot r2 x1
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-.100449 + * *
+----------------------------------------------------------------+
2.6 blood clotting score 11.2
plot r2 x2
.139377 +
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+----------------------------------------------------------------+
8 prognostic index 96
plot r2 x3
.139377 +
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+----------------------------------------------------------------+
23 enzyme function test 119
plot r2 x4
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-.100449 + * *
+----------------------------------------------------------------+
.74 liver function test 6.4
plot r2 p2
.139377 +
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+----------------------------------------------------------------+
1.60568 Fitted values 2.86227