gsDesign2 (version 1.1.2)

define_fail_rate: Define failure rate

Description

Define subject failure rate for a study with two treatment groups. Also supports stratified designs that have different failure rates in each stratum.

Usage

define_fail_rate(duration, fail_rate, dropout_rate, hr = 1, stratum = "All")

Value

A fail_rate data frame.

Arguments

duration

A numeric vector of ordered piecewise study duration interval.

fail_rate

A numeric vector of failure rate in each duration in the control group.

dropout_rate

A numeric vector of dropout rate in each duration.

hr

A numeric vector of hazard ratio between treatment and control group.

stratum

A character vector of stratum name.

Details

Define the failure and dropout rate of subjects for a study as following a piecewise exponential distribution. The duration are ordered piecewise for a duration equal to \(t_i - t_{i-1}\), where \(0 = t_0 < t_i < \cdots < t_M = \infty\). The failure rate, dropout rate, and hazard ratio in a study duration can be specified.

For a study with multiple strata, different duration, failure rates, dropout rates, and hazard ratios can be specified in each stratum.

Examples

# Define enroll rate
define_fail_rate(
  duration = c(3, 100),
  fail_rate = log(2) / c(9, 18),
  hr = c(.9, .6),
  dropout_rate = .001
)

# Define enroll rate with stratum
define_fail_rate(
  stratum = c(rep("Low", 2), rep("High", 2)),
  duration = 1,
  fail_rate = c(.1, .2, .3, .4),
  dropout_rate = .001,
  hr = c(.9, .75, .8, .6)
)