Unified Interface for Two Co-Primary Continuous Endpoints — twoCoprimary2Continuous • twoCoprimary

This function provides a unified interface for both power calculation and sample size determination for two co-primary continuous endpoints. Depending on which parameters are provided (sample sizes or power), the function automatically determines whether to calculate power or sample size.

Usage

twoCoprimary2Continuous(
  n1 = NULL,
  n2 = NULL,
  delta1,
  delta2,
  sd1,
  sd2,
  rho,
  power = NULL,
  r = NULL,
  alpha = 0.025,
  known_var = TRUE,
  nMC = 10000
)

Arguments

n1: Sample size for group 1 (treatment group). If NULL, will be calculated.
n2: Sample size for group 2 (control group). If NULL, will be calculated.
delta1: Mean difference for the first endpoint
delta2: Mean difference for the second endpoint
sd1: Common standard deviation for the first endpoint
sd2: Common standard deviation for the second endpoint
rho: Common correlation between the two outcomes
power: Target power (1 - beta). If NULL, will be calculated.
r: Allocation ratio (n1/n2). Required when calculating sample size.
alpha: One-sided significance level (typically 0.025 or 0.05)
known_var: Logical indicating whether variance is known (TRUE) or unknown (FALSE). Default is TRUE.
nMC: Number of Monte Carlo simulations when known_var = FALSE. Default is 10000.

Value

An object of class "twoCoprimary" containing either:

Power calculation results (when n1 and n2 are specified)
Sample size calculation results (when power and r are specified)

Details

This function serves as a unified interface similar to power.prop.test(). The function determines the operation mode based on which parameters are NULL:

If n1 and n2 are provided and power is NULL: calculates power
If power and r are provided and n1/n2 are NULL: calculates sample size

Exactly one of {(n1, n2), (power, r)} must be NULL.

Examples

# Calculate power given sample sizes
twoCoprimary2Continuous(
  n1 = 100, n2 = 100,
  delta1 = 0.5, delta2 = 0.5,
  sd1 = 1, sd2 = 1,
  rho = 0.3, alpha = 0.025,
  known_var = TRUE
)
#> 
#> Power calculation for two continuous co-primary endpoints
#> 
#>              n1 = 100
#>              n2 = 100
#>           delta = 0.5, 0.5
#>              sd = 1, 1
#>             rho = 0.3
#>           alpha = 0.025
#>       known_var = TRUE
#>          power1 = 0.942438
#>          power2 = 0.942438
#>  powerCoprimary = 0.893807
#> 

# Calculate sample size given target power
twoCoprimary2Continuous(
  delta1 = 0.5, delta2 = 0.5,
  sd1 = 1, sd2 = 1,
  rho = 0.3, power = 0.8,
  r = 1, alpha = 0.025,
  known_var = TRUE
)
#> 
#> Sample size calculation for two continuous co-primary endpoints
#> 
#>              n1 = 81
#>              n2 = 81
#>               N = 162
#>           delta = 0.5, 0.5
#>              sd = 1, 1
#>             rho = 0.3
#>      allocation = 1
#>           alpha = 0.025
#>            beta = 0.2
#>       known_var = TRUE
#>