cen_signedranktest function

Wilcoxcon Signed-Rank test for censored data

Performs a nonparametric Wilcoxon signed-rank test of whether the median difference between two columns of paired censored data equals 0. Uses the Pratt adjustment for pairs of equal or indistinguishable values.

cen_signedranktest(xd, xc, yd, yc, alternative = "two.sided", printstat = TRUE)

Arguments

• xd: The first column of data values plus detection limits
• xc: The column of censoring indicators for xd, where 1 (or TRUE) indicates a detection limit in the xd column, and 0 (or FALSE) indicates a detected value in xd.
• yd: The second column of data values plus detection limits, or a single number representing a standard / guideline value.
• yc: The column of censoring indicators for yd, where 1 (or TRUE) indicates a detection limit in the yd column, and 0 (or FALSE) indicates a detected value in yd. Not needed if yd is a single standard number.
• alternative: The usual notation for the alternate hypothesis. Default is “two.sided”. Options are “greater” or “less”.
• printstat: Logical TRUE/FALSE option of whether to print the resulting statistics in the console window, or not. Default is TRUE.

Returns

Prints a list of Wilcoxon Signed-Rank test with Pratt correction for ties statistics containing the following components:

• n Number of samples
• Z The value of the test statistic
• p.value the p-value of the test

Examples

data(atrazine)

cen_signedranktest(atrazine$June,atrazine$JuneCen,atrazine$Sept,atrazine$SeptCen)

References

Helsel, D.R., 2011. Statistics for censored environmental data using Minitab and R, 2nd ed. John Wiley & Sons, USA, N.J.

Page, E.B., 1963. Ordered Hypotheses for Multiple Treatments: A Significance Test for Linear Ranks. Journal of the American Statistical Association 58, 216–230. tools:::Rd_expr_doi("https://doi.org/10.2307/2282965")

Pratt, J.W., 1959. Remarks on Zeros and Ties in the Wilcoxon Signed Rank Procedures. Journal of the American Statistical Association 54, 655–667. tools:::Rd_expr_doi("https://doi.org/10.2307/2282543")