[EpiData-list] EpiData statistics documentation.
epidata-list at lists.umanitoba.ca
epidata-list at lists.umanitoba.ca
Mon May 30 09:30:02 CDT 2011
Lu 30 mai 2011
Hello EpiData users,
I'm a new subscriber to this list.
I used recently EpiData Analysis for a matched case-control with a
controls:case ratio of 38:19 or 2:1 (TAB DISEASE EXPOSURE COMMONID /O /t
/ex).
In the results output, and in the online help, for the crude table, I
could'nt find the type of test used, for example, which kind of Chi-square
(I was able to deduced it was uncorrected), of odds ratio (maximun
likelihoodestimate [MLE]?) and associated confidence interval (95%?), and
Fishers exact test (bilateral?). In the adjusted table, the OR [MLE?] is
provided with a CI (MLE and 95%?), followed by a Chi-square (unspecified
kind) and another p value (which kind?). The provided p values are rounded
at 3 digits after the decimal point. The last column provide p-exact
values (Fishers?), and the one on the adjusted line seems to refer to
another Chi-squared provided at the bottom of the table. Finally, the
exact p value for the adjusted results (e.g.: 0.3140) doesn't match with
the "probability of MLE >= value of MLE of OR (e.g. 6.10) if population OR
= 1.0" that I obtain (e.g..: 0.00196) with the command MATCH COMMONID
DISEASE EXPOSURE of Epi Info 6.04d DOS (which is probably equivalent to an
exact test), and seem discordant with the values of the CI (e.g.: 1.62 to
34.17).
Using the cohort approach (TAB DISEASE EXPOSURE /RR /t /ex), I found
similar lack of documentation about statistical tests.
I would suggest the following to the conceptors of EpiData:
- provide some documentation about statistical tests used in Analysis (do
any of the users have those answers?);
- provide notes at the bottom of tables to eliminate any ambiguities about
statistical methods;
- provide p values in the ajusted table with 4 digits after the decimal
point.
This software work pretty well, but need some ajustments. Keep on the good
work.
Best regards,
Réjean
Réjean Dion, M.D.
Médecin-conseil en santé publique (maladies infectieuses)
Institut national de santé publique du Québec (INSPQ) /
Laboratoire de santé publique du Québec (LSPQ)
20045, chemin Sainte-Marie,
Sainte-Anne-de-Bellevue (Québec)
Canada H9X 3R5
Tél.: (514) 457-2070 poste 325
Fax.: (514) 457-6346
Courriel / Lotus Notes: rejean.dion at inspq.qc.ca
More information about the EpiData-list
mailing list