Two_stage_sample_size {DTEBOP2} | R Documentation |
Calculate Sample Sizes for a Two-Stage Trial Design.
Description
Computes the required sample sizes for the interim and final analyses in a two-stage trial design, based on pre-specified operating characteristics such as desired power, type I error rate assumptions.
Usage
Two_stage_sample_size(
median.1,
median.2,
gprior.E_1 = NULL,
gprior.E_2 = NULL,
L,
U,
S_likely = (L + U)/2,
trunc.para = c(1, 1),
err1,
err2,
FUP,
rate,
weight = 0.5,
method = "optimal",
earlystop_prob = NULL,
seed = NULL
)
Arguments
median.1 |
Numeric. The overall median survival time for SOC. |
median.2 |
Numeric. The overall median survival time for the experimental arm. |
gprior.E_1 |
Optional. A numeric vector of length two, representing the shape and scale
parameters of the inverse-gamma prior for |
gprior.E_2 |
Optional. A numeric vector of length two, representing the inverse-gamma prior
for |
L |
Numeric. The lower bound of the separation time window. |
U |
Numeric. The upper bound of the separation time window. |
S_likely |
Numeric. The most likely separation time. Defaults to the midpoint of |
trunc.para |
Numeric vector of length two. Specifies the shape and scale parameters of the truncated gamma prior for the separation time. |
err1 |
Numeric. The pre-specified type I error rate (e.g., |
err2 |
Numeric. The pre-specified type II error rate (i.e., |
FUP |
Numeric. The duration of follow-up per patient (in months or years). Default is 6. |
rate |
Numeric. The recruitment rate (e.g., patients per month or year). |
weight |
Numeric. Weight given to the expected sample size under |
method |
Character. Specifies which method to use:
|
earlystop_prob |
Optional. Numeric. If specified, ensures that the probability of early
stopping under |
seed |
Optional integer. If provided, sets the seed for reproducibility. |
Value
A numeric vector of length 2. The first element is the required sample size for interim analysis, and the second element is the total sample size for final analysis in a two-stage design.
Examples
# Define design parameters
median.1 <- 4 # Median survival for standard-of-care
median.2 <- 6 # Median survival for experimental arm
L <- 2 # Lower bound of separation time
U <- 2.5 # Upper bound of separation time
S_likely <- 2.28 # Most likely separation time
rate <- 6 # Accrual rate (patients/month)
FUP <- 6 # Follow-up duration (months)
err1 <- 0.1 # Type I error
err2 <- 0.15 # Type II error
Two_stage_sample_size(
median.1 = median.1,
median.2 = median.2,
L = L,
U = U,
S_likely = S_likely,
err1 = err1,
err2 = err2,
FUP = FUP,
rate = rate,
weight = 0.5,
method = "optimal"
)