Hi, new in R and I would like to start with calculating an incidence rate. My data is imported into R from a tab delimited txt file, as shown below: ID DATE_BIRTH DATE_UNT EVENT TIME_EV 1 4867 08/02/1959 19/10/2001 1 31 2 52 15/07/1941 08/02/1999 1 6 3 63 02/01/1946 11/02/1999 1 6 4 710 21/10/1965 23/03/1999 0 10 5 1808 07/05/1952 18/06/1999 1 7 6 554 19/08/1947 15/03/1999 0 10 ... event (EVENT=1) censoring (EVENT=0) How do I calculate the incidence rate in R for different strata of age? 1) number of events (EVENT) / personmonths to event or censoring (TIME_EV) 2) number of events (EVENT) / 12 personmonths to event or censoring (TIME_EV) I am lost here, and did not succeed to understand epiR, and the option to create a matrix for simple incidence rates, and not incidence rate ratios. If anyone could help me out with a simple to understand syntaxt to get further, I would aprreciate so much and thanks in advance!! nb -- View this message in context: http://r.789695.n4.nabble.com/epiR-Incidence-rate-beginner-question-on-syntax-tp4645896.html Sent from the R help mailing list archive at Nabble.com.