R/B_Index.R

In Ctross/SkewCalc: Estimation Of Reproductive Skew

#' B index a la Nonacs.
#'
#' @param r A vector of RS values.
#' @param t A vector of exposure times.
#' @return The B index.
#' @examples
#' set.seed(1)
#' RS = rpois(100, 5) 
#' Age = rpois(100, 45)
#' B_index(RS, Age)

B_index = function(r, t){   
  if(min(t) <= 0){              
  return(NA)
  } 
  else{                      
    T = sum(t)
    Nbar = T / max(t)
    R = sum(r)
   
      if(R > 0){
	B = sum(((r / R) - (t / T))^2) - ((1 / R) * (1 - (1 / Nbar)))
	} 
      else {
	B = NA
	}
	return(B)
  }
}