about odds，why the two command get the different results？

[Zhang xiangyang]

a list of numbers，as follows

	drug
	used	unused
case	55	128
control	19	164

when use command cci 55 128 19 164 ，i get a odds= 3.708882，95%CI（2.039667，6.941302）
but when use command logit,or
the results like this

logit,or

Logistic regression Number of obs = 366
LR chi2(1) = 22.73
Prob > chi2 = 0.0000
Log likelihood = -242.32729 Pseudo R2 = 0.0448

------------------------------------------------------------------------------
y | Odds Ratio Std. Err. z P>|z| [95% Conf. Interval]
-------------+----------------------------------------------------------------
x | 3.708882 1.079555 4.50 0.000 2.096434 6.561524
_cons | .7804878 .0920515 -2.10 0.036 .6194049 .9834621
------------------------------------------------------------------------------
Note: _cons estimates baseline odds.

the odds is same，but the 95%CI is different，why？

[Clyde Schechter]

The two procedures use different methods to compute the confidence intervals. -cci- uses an exact binomial approach, whereas -logit- uses the usual approach for maximum likelihood estimation, which is based on the information matrix. Notice that the results are quite similar, though not exactly the same. If you want all the details, consult the chapters in the PDF manuals that come installed with your Stata. Each chapter contains a section on Methods and Formulas that will tell you everything.

[Zhang xiangyang]

thanks for your reply