cenperm2 | R Documentation |
Performs a permutation test of differences in means between two groups of censored data.
cenperm2(y1, y2, grp, R = 9999, alternative = "two.sided", printstat = TRUE)
y1 |
The column of data values plus detection limits |
y2 |
The column of indicators, where 1 (or |
grp |
Grouping or factor variable. Can be either a text or numeric value indicating the group assignment. |
R |
The number of permutations used. Default is 9999 |
alternative |
indicates the alternative hypothesis and must be one of " |
printstat |
Logical |
Because this is a permutation test it avoids the problem with MLE tests (cen2means
) that assume a normal distribution. No values are modeled as below zero and p-values
are trustworthy. Ranges in means and p-values are due to interval-censoring of censored data means.
Permutation test results with the number of permutations, range in group means and their difference, and range in p-value
.
Good, P., 2000. Permutation Tests: A Practical Guide to Resampling Methods for Testing Hypotheses, 2nd ed, Springer Series in Statistics. Springer-Verlag, New York, NY. \Sexpr[results=rd]{tools:::Rd_expr_doi("https://doi.org/10.1007/978-1-4757-3235-1")}
Helsel, D.R., 2011. Statistics for Censored Environmental Data using Minitab and R, 2nd ed. John Wiley & Sons, USA, N.J.
Shapiro, S.S., Francia, R.S., 1972. An approximate analysis of variance test for normality. Journal of the American Statistical Association 67, 215–216.
data(PbHeron)
cenperm2(PbHeron$Liver,PbHeron$LiverCen,PbHeron$DosageGroup,alternative="t")
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