# contrMat: Contrast Matrices In multcomp: Simultaneous Inference in General Parametric Models

## Description

Computes contrast matrices for several multiple comparison procedures.

## Usage

 ```1 2 3 4``` ```contrMat(n, type = c("Dunnett", "Tukey", "Sequen", "AVE", "Changepoint", "Williams", "Marcus", "McDermott", "UmbrellaWilliams", "GrandMean"), base = 1) ```

## Arguments

 `n` a (possibly named) vector of sample sizes for each group. `type` type of contrast. `base` an integer specifying which group is considered the baseline group for Dunnett contrasts.

## Details

Computes the requested matrix of contrasts for comparisons of mean levels.

## Value

The matrix of contrasts with appropriate row names is returned.

## References

Frank Bretz, Torsten Hothorn and Peter Westfall (2010), Multiple Comparisons Using R, CRC Press, Boca Raton.

Frank Bretz, Alan Genz and Ludwig A. Hothorn (2001), On the numerical availability of multiple comparison procedures. Biometrical Journal, 43(5), 645–656.

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17``` ``` n <- c(10,20,30,40) names(n) <- paste("group", 1:4, sep="") contrMat(n) # Dunnett is default contrMat(n, base = 2) # use second level as baseline contrMat(n, type = "Tukey") contrMat(n, type = "Sequen") contrMat(n, type = "AVE") contrMat(n, type = "Changepoint") contrMat(n, type = "Williams") contrMat(n, type = "Marcus") contrMat(n, type = "McDermott") ### Umbrella-protected Williams contrasts, i.e. a sequence of ### Williams-type contrasts with groups of higher order ### stepwise omitted contrMat(n, type = "UmbrellaWilliams") ### comparison of each group with grand mean of all groups contrMat(n, type = "GrandMean") ```

multcomp documentation built on May 2, 2019, 8:54 a.m.