Description Usage Arguments Details Value References See Also

Performs a parametric test of differences in means between groups of censored data, followed by a parametric Tukey's multiple comparison test.

1 |

`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. |

`LOG` |
Indicator of whether to compute tests in the original units, or on their logarithms. The default is to use the logarithms ( |

`printstat` |
Logical |

Test is computed using Maximum Likelihood Estimation. When a gaussian distribution model is used (LOG=FALSE) modeled values may fall below zero, producing unreal p-values (often lower than they should be). Because of this, testing in log units is preferable and is the default.

Returns the Maximum Likelihood Estimation (MLE) comparison results including Chi-Squared value, degrees of freedom and `p-value`

of the test. Test assumes log-normal(`LOG=TRUE`

) or normal(`LOG=FALSE`

) distribution of residuals from group means.

Tukey's multiple comparison p-values of pairwise differences in group means are also printed.

Group Names of groups (NOTE:

`== 0`

indicates null hypothesis of "equals zero").-
`Estimate`

Estimated difference between group means. -
`Std. Error`

Standard error of estimate. -
`z value`

Test statistic. -
`Pr(>|z|)`

P-values for test that difference in means equals zero.

Helsel, D.R., 2011. Statistics for Censored Environmental Data using Minitab and R, 2nd ed. John Wiley & Sons, USA, N.J.

#' @examples data(PbHeron) cenanova(PbHeron$Liver,PbHeron$LiverCen,PbHeron$DosageGroup)

cenanova(PbHeron$Liver,PbHeron$LiverCen,PbHeron$DosageGroup,LOG=FALSE)

survival::survreg

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