"cat.." <cat.b41@GMAIL.COM> wrote >> >> I have limited experience in time-to-event data analysis. I requested, >> in a statistical analysis plan for an observational study, to plot theKaplan-Meiercurves for 2 groups of patients on a single plot, >> together with the 95% CIs at specific timepoints. >> >> When 95% CIs do not overlapp at a given timepoint, is it correct to >> draw the conclusion that disc rates are significantly different at >> this timepoint ? >> >> Reversely, when they overlapp, is it correct to infer that the disc >> rates at that timepoint are NOT significantly different ? >> >> Thanks for your feedback. This is quite urgent as I need to give my >> feedback early this coming week. >> >> Catherine. > >Has anyone an idea ?

Yes to the first question, no to the second question.

That is, if the 95% CI do not overlap, then p will be below .05; but p can be below .05 even if the CIs do overlap.

This was recently discussed, in some depth, on the MEDSTATS list; here:

http://bit.ly/XN075

or, in its original form http://groups.google.com/group/medstats/search?group=medstats&q=ci++p+overlap&qt_g=Search+this+group

or google MEDSTATS, p, CI, overlap

the topic of the thread was "subgroup analysis"

HTH

Peter

Peter L. Flom, PhD Statistical Consultant Website: www DOT peterflomconsulting DOT com Writing; http://www.associatedcontent.com/user/582880/peter_flom.html Twitter: @peterflom