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Re: st: regress
From
Richard Williams <[email protected]>
To
[email protected], [email protected]
Subject
Re: st: regress
Date
Tue, 27 Aug 2013 12:23:22 -0500
This seems to be more of a substantive question for economics than it
does a statistics or Stata question. But if I thought the sign for a
coefficient seemed odd, I would (a) make sure all my coding is ok,
and (b) check the bivariate correlations. If the bivariate
correlation was positive and the regression coefficient was negative,
I would start thinking about some sort of suppressor effect. Maybe
greater amounts of labor indicate lower levels of efficiency, at
least once other variables are taken into account. But do some
reading in economics or get the opinion of someone in the field.
At 10:32 AM 8/27/2013, Rezgar Mohammed wrote:
Hello,
I am a beginner in Econ. I would like to test the effect of some
factors on the production of specific output using the Cobb-Douglass
production function. I would like to know if you have any concerns
about the results.
Y represents output, x1 labor, x2 fertilizer, x3 land, x4 seed and x5
is capital. I wonder why the x1 coefficient is negative for example.
reg lny lnx1 lnx2 lnx3 lnx4 lnx5
Source | SS df MS Number of
obs = 160
-------------+------------------------------ F( 5, 154) =22942.46
Model | 1.13880167 5 .227760334 Prob >
F = 0.0000
Residual
| .001528829 154 9.9275e-06 R-squared = 0.9987
-------------+------------------------------ Adj R-squared = 0.9986
Total | 1.1403305 159 .00717189 Root
MSE = .00315
------------------------------------------------------------------------------
lny | Coef. Std. Err. t P>|t| [95%
Conf. Interval]
-------------+----------------------------------------------------------------
lnx1
| -.0398971 .0008289 -48.13 0.000 -.0415346 -.0382596
lnx2
| 1.063405 .0033848 314.17 0.000 1.056719 1.070092
lnx3
| -.0008994 .0005395 -1.67 0.098 -.0019652 .0001664
lnx4
| .0023421 .0024396 0.96 0.339 -.0024772 .0071615
lnx5
| .0025708 .000884 2.91 0.004 .0008245 .0043171
_cons
| -.3304083 .0228141 -14.48 0.000 -.3754774 -.2853393
------------------------------------------------------------------------------
I tested for heteroskedasticity and auto-correlation but nothing changes.
Thank you.
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-------------------------------------------
Richard Williams, Notre Dame Dept of Sociology
OFFICE: (574)631-6668, (574)631-6463
HOME: (574)289-5227
EMAIL: [email protected]
WWW: http://www.nd.edu/~rwilliam
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