R/nCont.R

In PracTools: Tools for Designing and Weighting Survey Samples

nCont <- function(CV0=NULL, V0=NULL, S2=NULL, ybarU=NULL, N=Inf, CVpop=NULL){
    n.sam <- NULL
    if (sum(sapply(list(CV0, V0, S2, ybarU, CVpop), is.null)) == 5)
        stop("No parameters specified\n")

    if (sum(sapply(list(CV0, V0), is.null)) == 2)
        stop("At least one of CV0 or V0 must be specified\n")
    if (sum(sapply(list(CV0, V0), is.null)) == 0)
        stop("Only one of CV0 or V0 can be specified\n")
    N.etal.chk <- any(N <= 0, S2 <= 0, CV0 <= 0, V0 <= 0, CVpop <= 0)
    if (N.etal.chk) stop("N, S2, CV0, V0, and CVpop cannot be <= 0.\n")

    if (sum(sapply(list(S2, ybarU, CVpop), is.null)) == 0){
        warning("S2, ybarU, and CVpop all specified. CVpop ignored.\n")
    }
    if (sum(sapply(list(CVpop, N, CV0), is.null)) == 0)
            n.sam <- CVpop^2 / (CV0^2 + CVpop^2/N)

    if (sum(sapply(list(S2, ybarU, N, CV0), is.null)) == 0){
            CVpop <- sqrt(S2)/ybarU
            n.sam <- CVpop^2 / (CV0^2 + CVpop^2/N)
    }
    if (sum(sapply(list(S2, N, V0), is.null)) == 0){
            n.sam <- S2 / (V0 + S2/N)
    }
    if (is.null(n.sam)) stop("Parameter combination is wrong. Check inputs.\n")
    else n.sam
}