 Solution

Survival data describe the time $T$ from a specified origin to an event, together with covariates and information about how observation begins and ends. Some event times are observed exactly; others are subject to censoring or excluded by truncation. Here the time origin is the opening of a business and the event is its closure. An observed record contains an entry age, an exit age, an event indicator and the business characteristics. The time origin and observation mechanism are part of the data specification.