followup.time: followup.time

In tvtools: Comprehensive Tools for Panel Data Analysis - 'tvtools'

followup.time

Description

Computes the total or maximum follow-up time for each subject in a panel data structure, accounting for observation endpoints like death, loss to follow-up, or study conclusion.

Usage

followup.time(
  dat,
  id.name = "id",
  t1.name = "t1",
  t2.name = "t2",
  followup.name = "followup.time",
  calculate.as = "total",
  append.to.data = FALSE
)

Arguments

dat	A data.frame structured as panel data.
id.name	The character name of the identifying variable within dat, used to track subjects across multiple rows.
t1.name	The character name of the time variable within dat representing the start (left endpoint) of observation intervals.
t2.name	The character name of the time variable within dat representing the end (right endpoint) of observation intervals.
followup.name	The character name for the new variable to display the calculated follow-up time for each subject.
calculate.as	A character value specifying the calculation method for follow-up time: "max" for the maximum observed time point for each subject, or "total" for the total observed time across all records for each subject (default). Note: "max" and "total" yield the same result when records start at time 0, have no gaps, and don't overlap.
append.to.data	A logical indicating whether to append the calculated follow-up time as a new column to the original data.frame (TRUE), or return it as a separate data frame (FALSE, default).

Value

Returns a modified version of the input data frame or a new data frame based on the append.to.data parameter. If append.to.data is TRUE, the original data frame is returned with an additional column named as specified by followup.name, containing the calculated follow-up times for each subject. If FALSE, a new data frame is returned containing the id.name and the calculated follow-up times under the followup.name column. This functionality is essential for analyses that require understanding the duration of subject participation or observation within the study period.

tvtools documentation built on Oct. 8, 2024, 5:09 p.m.