Distribution Use this option to select a distribution to model the time to the event. Available distributions are described in the table below: Method Description Exponential Assumes an exponential distribution. Gamma Assumes a generalized gamma distribution. LLogistic Assumes a log-logistic distribution. LNormal Assumes a log-normal distribution. Logistic Assumes a logistic distribution. Normal Assumes a normal distribution. Weibull Assumes a Weibull distribution. Refer to the SAS PROC LIFEREG documentation for more information. To Specify a Distribution: Select the desired distribution by clicking the appropriate radio button.