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@inspq.qc.ca