Valve seats wear out in certain diesel engines, each with 16 valve seats.
The dataset served as an example of recurrence data in Nelson (1995),
which consists of valve-seat replacements on 41 engines in a fleet.
The covariates are named
ID: The engine number;
Days: Engine age in days;
No.: Event indicator, '1' for a valve-seat replacement
and, '0' for the censoring age of an engine.
A data frame with 89 rows and 3 variables.
Nelson, W. (1995), Confidence Limits for Recurrence Data-Applied to Cost or Number of Product Repairs, Technometrics, 37, 147–157.