Determines the total number of stages each individual has reached by a
specified analysis time t_s, based on their arrival times
t1, ..., t_{K+1}.
Arguments
- df
A data frame containing columns t1, t2, ..., t_{K+1}
representing the times at which each individual reaches each stage.
- t_s
A numeric value specifying the analysis time point.
- K
An integer specifying the number of treatment stages (decision
points).
Value
An integer vector of length nrow(df) indicating the number of
stages each individual has reached by time t_s. Values range from 0
(not yet enrolled) to \(K+1\) (outcome observed).