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st: Re: logistic reg version 8 & 11
From
Ricardo Ovaldia <[email protected]>
To
Statalist <[email protected]>
Subject
st: Re: logistic reg version 8 & 11
Date
Thu, 9 Sep 2010 09:26:03 -0700 (PDT)
Here is an example using the auto data:
. sysuse auto, clear
(1978 Automobile Data)
. version 8
. xi:logistic foreign i.rep78
i.rep78 _Irep78_1-5 (naturally coded; _Irep78_1 omitted)
note: _Irep78_2 != 0 predicts failure perfectly
_Irep78_2 dropped and 8 obs not used
Logistic regression Number of obs = 61
LR chi2(3) = 23.66
Prob > chi2 = 0.0000
Log likelihood = -27.444671 Pseudo R2 = 0.3012
------------------------------------------------------------------------------
foreign | Odds Ratio Std. Err. z P>|z| [95% Conf. Interval]
-------------+----------------------------------------------------------------
_Irep78_3 | 1.03e+07 . . . . .
_Irep78_4 | 9.24e+07 7.12e+07 23.83 0.000 2.04e+07 4.18e+08
_Irep78_5 | 4.16e+08 4.12e+08 20.03 0.000 5.97e+07 2.90e+09
------------------------------------------------------------------------------
Note: 2 failures and 0 successes completely determined.
. version 11
. xi:logistic foreign i.rep78
i.rep78 _Irep78_1-5 (naturally coded; _Irep78_1 omitted)
note: _Irep78_2 != 0 predicts failure perfectly
_Irep78_2 dropped and 8 obs not used
Logistic regression Number of obs = 61
LR chi2(3) = 23.66
Prob > chi2 = 0.0000
Log likelihood = -27.444671 Pseudo R2 = 0.3012
------------------------------------------------------------------------------
foreign | Odds Ratio Std. Err. z P>|z| [95% Conf. Interval]
-------------+----------------------------------------------------------------
_Irep78_2 | (omitted)
_Irep78_3 | 788893.3 1.49e+09 0.01 0.994 0 .
_Irep78_4 | 7101032 1.34e+10 0.01 0.993 0 .
_Irep78_5 | 3.20e+07 6.02e+10 0.01 0.993 0 .
------------------------------------------------------------------------------
Ricardo Ovaldia, MS
Statistician
Oklahoma City, OK
Ricardo Ovaldia, MS
Statistician
Oklahoma City, OK
--- On Thu, 9/9/10, Ricardo Ovaldia <[email protected]> wrote:
> From: Ricardo Ovaldia <[email protected]>
> Subject: logistic reg version 8 & 11
> To: "Statalist" <[email protected]>
> Date: Thursday, September 9, 2010, 11:19 AM
>
> I wrote a program a while back using version 8 and I notce
> the -logistic- gives different results. The results under
> version 8 differ from those under version 11. Why is this?
> Which is correct?
>
> . version 8
>
> . xi: logistic case i.x
> i.x
> _Ix_1-3
> (_Ix_1 for x==A_A omitted)
>
> Logistic regression
>
> Number of
> obs = 1195
>
>
>
> LR chi2(2) =
> 5.04
>
>
>
> Prob > chi2 =
> 0.0806
> Log likelihood = -665.32155
>
> Pseudo R2
> = 0.0038
>
> ------------------------------------------------------------------------------
> case | Odds
> Ratio Std. Err. z
> P>|z| [95% Conf.
> Interval]
> -------------+----------------------------------------------------------------
> _Ix_2
> | 2.14e-09
> . .
> .
> . .
> _Ix_3
> | 4.95e-09 3.08e-09 -30.80 0.000
> 1.47e-09 1.67e-08
> ------------------------------------------------------------------------------
> Note: 0 failures and 1 success completely determined.
>
> . version 11
>
> . xi: logistic case i.x
> i.x
> _Ix_1-3
> (_Ix_1 for x==A_A omitted)
>
> Logistic regression
>
> Number of
> obs = 1195
>
>
>
> LR chi2(2) =
> 5.04
>
>
>
> Prob > chi2 =
> 0.0806
> Log likelihood = -665.32156
>
> Pseudo R2
> = 0.0038
>
> ------------------------------------------------------------------------------
> case | Odds
> Ratio Std. Err. z
> P>|z| [95% Conf.
> Interval]
> -------------+----------------------------------------------------------------
> _Ix_2
> | 1.02e-06 .0003817
> -0.04 0.971
> 0
> .
> _Ix_3
> | 2.36e-06 .0008842
> -0.03 0.972
> 0
> .
> ------------------------------------------------------------------------------
>
>
>
>
> Ricardo Ovaldia, MS
> Statistician
> Oklahoma City, OK
>
>
>
>
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