R/CCC.R

In Prof-ThiagoOliveira/lcc: Longitudinal Concordance Correlation

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# Package: lcc                                                        #
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# File: CCC.R                                                         #
# Contains: CCC function                                              #
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# Written by Thiago de Paula Oliveira                                 #
# copyright (c) 2017-18, Thiago P. Oliveira                           #
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# First version: 11/10/2017                                           #
# Last update: 25/11/2023                                            #
# License: GNU General Public License version 2 (June, 1991) or later #
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##' @title Internal Function to Compute the Sampled Concordance
##'   Correlation Values.
##'
##' @description This function computes the sampled concordance correlation
##'   coefficient (CCC) between two numeric vectors. It is used internally
##'   for statistical analysis.
##'
##' @param Y1 A numeric vector.
##' @param Y2 A numeric vector, typically paired with Y1.
##'
##' @return The concordance correlation coefficient between Y1 and Y2.
##'
##' @importFrom stats var cov
##'
##' @keywords internal
##' @examples
##' # Example usage:
##' # CCC(c(1, 2, 3), c(3, 2, 1))
CCC <- function(Y1, Y2) {
  m1 <- mean(Y1)
  m2 <- mean(Y2)
  S12 <- cov(Y1, Y2)
  CCC_lin <- 2 * S12 / (var(Y1) + var(Y2) + (m1 - m2)^2)
  return(CCC_lin)
}