Today I wanted to experiment with different distributions an to see the hazard rates they imply. So I eventually ended up with this, which uses the hist object's handy $density and the cumsum function in R: x <- c(rweibull(21000,0.5,0.7)) #create "breaks" vector to go into histogram #need last break bigger than max(x) y <- seq(0,max(x)+2) histx <- hist(x,freq=FALSE,breaks=y) cumProb<- cumsum(histx$density) survival <- 1-cumProb survival<- c(1,survival) survival <- survival[1:length(histx$density)] hazard <- histx$density / survival plot(hazard,type="l") par(ask=TRUE) retention<- 1-hazard plot(retention,type="l",xlim=c(0,95)) This works the way I expect, except that there is a little numerical imprecision in the high end of the values for the cumulative probability. The vector cumProb does not have 1.0 as its last element, but rather something close, like 0.99997 or such. I know the values in cumProb are correct for the left end of the vector, just not the right end. That has implications for the calculation of hazard and retention curve values. Do you have any tips for me? -- Paul E. Johnson email: pauljohn at ukans.edu Dept. of Political Science http://lark.cc.ukans.edu/~pauljohn University of Kansas Office: (785) 864-9086 Lawrence, Kansas 66045 FAX: (785) 864-5700 -.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.-.- r-help mailing list -- Read http://www.ci.tuwien.ac.at/~hornik/R/R-FAQ.html Send "info", "help", or "[un]subscribe" (in the "body", not the subject !) To: r-help-request at stat.math.ethz.ch _._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._._