The FREQ statement specifies a variable that provides frequency counts for each observation in the input data set. If is the value of the FREQ variable in the input data set for an observation, then that observation is weighted by . The log-likelihood function for maximum likelihood estimation is multiplied by . If is not an integer, the integer part of is used in creating probability plots.
You can also use the FREQ statement in conjunction with the NENTER statement to specify interval-censored data having a special structure; these data are called readout data. The FREQ statement specifies a variable in the input data set that determines the number of units failing in each interval. See the section Weibull Analysis of Interval Data with Common Inspection Schedule for an example that uses the FREQ statement with readout data.
You can also use the FREQ statement in conjunction with the NENTER statement to specify recurrent events data when the event times are grouped into intervals, rather than being observed exactly. The FREQ statement specifies a variable in the input data set that determines the number of events in each interval.
You can use the FREQ statement with the MCFPLOT and MODEL statements for exact age data to provide frequency counts for entire recurrence histories. If is the value of the FREQ variable at a censor time, the history of recurrences for the corresponding system is replicated independently times. Values of the FREQ variable at times other than censor times are not used; they can be any value or missing without affecting the analysis.