The function dataprep provides a ready-to-use data format that can be directly used in the function ciregic. The returned data frame consists of id, v, u, c, and covariates as columns. The v and u indicate time window with the last observation time before the event and the first observation after the event. The c represents a type of event, for example, c = 1 for the first cause of failure, c = 2 for the second cause of failure, and c = 0 for the right-censored. For individuals having one time record with the event, the lower bound v will be replaced by zero, for example (0, v]. For individuals having one time record without the event, the upper bound u will be replaced by Inf, for example (v, Inf].