You should consider "prop.test" or "binom.test". The problem you will find is that these functions are not intended to do what you want but to give you one confidence interval at a time. However a starting point could be : I<-sample(1:50) #the numerator N<-sample(50:200, 50) #the denominator conf.intervals<-t( sapply( mapply(binom.test, SIMPLIFY=F, x=I, n=N), "[[", "conf.int") ) cbind(I, N, P=I/N, conf.int) best whishes, Stefano -----Messaggio originale----- Da: Darren Shaw [mailto:Darren.Shaw at ed.ac.uk] Inviato: luned?? 12 luglio 2004 17.45 A: r-help at stat.math.ethz.ch Oggetto: [R] proportions confidence intervals Dear R users this may be a simple question - but i would appreciate any thoughts does anyone know how you would get one lower and one upper confidence interval for a set of data that consists of proportions. i.e. taking a usual confidence interval for normal data would result in the lower confidence interval being negative - which is not possible given the data (which is constrained between 0 and 1) i can see how you calculate a upper and lower confidence interval for a single proportion, but not for a set of proportions many thanks Darren Shaw ----------------------------------------------------------------- Dr Darren J Shaw Centre for Tropical Veterinary Medicine (CTVM) The University of Edinburgh Scotland, EH25 9RG, UK ______________________________________________ R-help at stat.math.ethz.ch mailing list https://www.stat.math.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide! http://www.R-project.org/posting-guide.html