Madeleine Rossi (asker) Oct 6, 2011:

Wish we could buy some extra hours on eBay... Kinda plug-ins Higg's boson-style, you know?

SJLD Oct 6, 2011:

part of my master plan - if only there were 48 hours in every day ;-)

Madeleine Rossi (asker) Oct 6, 2011:

Brilliant! Thank you for TEACHING me basic stat analysis... :-))))

SJLD Oct 6, 2011:

60%:40% = 3:2 - in other words, for every three patients taking drug1, there are two taking drug2.

Madeleine Rossi (asker) Oct 6, 2011:

Hi there, yes you are right and I am sorry, I thought it was "easy" to understand and only a terminology issue (my pathetic relationship to maths and stats)! here is some context (long one...) about this "Retrospective and Prospective Observational Study" : We plan to enroll 400 subjects with 60% for DRUG1 and 40% on DRUG2. Enrollment of subjects will be retrospective to minimize selection bias. Only subjects who were initiated on treatment within the last 3 months before the date the site was informed about the study are eligible (Figure 1). This prevents the enrollment of selected patients after the investigator was informed about the details of the planned study. Following a structured enrollment procedure will also allow controlling somewhat for the 3:2 treatment split although no stratification of subjects in this observational setting is permitted. For the rationale concerning sample size justification refer to Section XX.

SJLD Oct 6, 2011:

Hard to know what is meant without more info - what is being studied for example? But could mean 3 groups and 2 treatments (A and B). Group 1 treatment A, gp 2 treatment B, gp 3 treatment A+B, for example.
I'm not a native speaker of French, but I am a native English speaker and an epidemiologist so maybe I can help if given the necessary info ;-)