Description Usage Arguments Details Value References Examples

Performs a permutation test of differences in means between two groups of censored data.

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`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. doi: 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.

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