I would like EpiData Analysis to state that its OR is CMLE (at least in the existing help file). AND add (regular) OR as well if you may, because both are there in OpenEpi. If you follow OpenEpi I wonder why you use Fisherexact p only instead of Mid-P Exact as well(Mid-P Exact is the preferred by the author(s) at OpenEpi by the way in this case). By the way, EpiInfo 6 Statcalc calculates OR not by CMLE and obtains same as SPSS does.
--- On Mon, 10/13/08, epidata-list@lists.umanitoba.ca epidata-list@lists.umanitoba.ca wrote:
From: epidata-list@lists.umanitoba.ca epidata-list@lists.umanitoba.ca Subject: Re: [EpiData-list] OR error report To: epidata-list@lists.umanitoba.ca Date: Monday, October 13, 2008, 7:09 PM EpiData provides the conditional maximum likelihood estimate for OR, which is normally accepted as a better estimate.
If you put your data into OpenEpi you can see the differences between estimates and confidence intervals:
Jamie
epidata-list@lists.umanitoba.ca wrote:
This is concerning to v2.0.3.129 EpiData Analysis. Recently I dig in to OR and RR using said version. The data base I used was one used in SPSS to do the
same.
In essence, the calculation result were different from
what I obtained
from SPSS, given that I recoded outcomes and risk
exposures, i.e. 1=2, 2=1.
(SPSS uses ascending order for both outcomes and risk
exposures, 1 codes as positive 2 as negative which is just the opposite of EpiData Analysis handling)
EpiData Analysis result: OR=3.68 (95% CI:
1.03-11.89)Fishersexact p= 0.0224
SPSS result: OR=3.72 (3.7158) (95% CI:
1.27039-10.86604) Fishersexact p=.02239
Whereas RR resulted the same. EpiData Analysis: RR = 2.86 (95% CI:
1.31-6.24)Fishersexact p= 0.0224
SPSS: RR = 2.86 (2.85789) (95% CI: 1.30965-6.23646) USING CELL OBSERVED FREQUENCIES AS A=6, B=13, C=20,
D=161 WHEREAS A:C1R1, B:C2R1, C:C1R2, D:C2R2.
I wonder if the formula used by EpiData Analysis is
OR=(A/C)/(B/D)=(A/B)/(C/D)= (AD)/(BC). The OR as well as corresponding CI are different from that of SPSS
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