PMCMRplus (version 1.6.0)

tamhaneDunnettTest: Tamhane-Dunnett Many-to-One Comparison Test

Description

Performs Tamhane-Dunnett's multiple comparisons test with one control. For many-to-one comparisons in an one-factorial layout with normally distributed residuals and unequal variances Tamhane-Dunnett's test can be used. A total of $m=k-1$ hypotheses can be tested. The null hypothesis H${}_i:{\mu }_0(x)={\mu }_i(x)$ is tested in the two-tailed test against the alternative A${}_i:{\mu }_0(x)\ne {\mu }_i(x),1\le i\le k-1$.

The p-values for the test are calculated from the multivariate t distribution as implemented in the function pmvt.

Usage

tamhaneDunnettTest(x, ...)
# S3 method for default
tamhaneDunnettTest(x, g, alternative = c("two.sided", "greater", "less"), ...)
# S3 method for formula
tamhaneDunnettTest(
  formula,
  data,
  subset,
  na.action,
  alternative = c("two.sided", "greater", "less"),
  ...
)
# S3 method for aov
tamhaneDunnettTest(x, alternative = c("two.sided", "greater", "less"), ...)

Arguments

x

a numeric vector of data values, a list of numeric data vectors or a fitted model object, usually an aov fit.

…

further arguments to be passed to or from methods.

g

a vector or factor object giving the group for the corresponding elements of "x". Ignored with a warning if "x" is a list.

alternative

the alternative hypothesis. Defaults to "two.sided".

formula

a formula of the form response ~ group where response gives the data values and group a vector or factor of the corresponding groups.

data

an optional matrix or data frame (or similar: see model.frame) containing the variables in the formula formula. By default the variables are taken from environment(formula).

subset

an optional vector specifying a subset of observations to be used.

na.action

a function which indicates what should happen when the data contain NAs. Defaults to getOption("na.action").

Value

A list with class "PMCMR" containing the following components:

method

a character string indicating what type of test was performed.

data.name

a character string giving the name(s) of the data.

statistic

lower-triangle matrix of the estimated quantiles of the pairwise test statistics.

p.value

lower-triangle matrix of the p-values for the pairwise tests.

alternative

a character string describing the alternative hypothesis.

p.adjust.method

a character string describing the method for p-value adjustment.

model

a data frame of the input data.

dist

a string that denotes the test distribution.

References

OECD (ed. 2006) Current approaches in the statistical analysis of ecotoxicity data: A guidance to application - Annexes. OECD Series on testing and assessment, No. 54.

See Also

pmvt, welchManyOneTTest

Examples

# NOT RUN {
set.seed(245)
mn <- c(1, 2, 2^2, 2^3, 2^4)
x <- rep(mn, each=5) + rnorm(25)
g <- factor(rep(1:5, each=5))

fit <- aov(x ~ g - 1)
shapiro.test(residuals(fit))
bartlett.test(x ~ g - 1)
anova(fit)
## works with object of class aov
summary(tamhaneDunnettTest(fit, alternative = "greater"))

# }