Hi All, I have data in the following format: Inspection #failures Month/Year 01/99 5 02/99 20 06/99 3 01/02 3 for 11 years ... the prob of failure on demand per month pfd is #Total failures / sample size(=total components * 11yrs * 12months). I am required to cross-check pfd by other means. Can I fit a weibull or lognormal plot to this count data and find the failure probability or reliability from this data? exact failure times are not known..only the number of failures in the month is known. please suggest an appropriate method / R code. Thanks, Tims [[alternative HTML version deleted]]