multgee (version 1.5.0)

matrixLOR: Creating A Probability Matrix With Specified Local Odds Ratios

Description

Utility function to create a square probability matrix that satifies the specified local odds ratios structure.

Usage

matrixLOR(x)

Arguments

x

a square matrix with positive entries that describes the desired local odds ratios matrix.

Value

• Returns a square probability matrix that satisfies the local odds ratios structure defined by x.

Warning

Caution is needed for local odds ratios close to zero.

Details

This function is designed to ease the construction of the LORterm argument in the functions nomLORgee and ordLORgee.

See Also

nomLORgee and ordLORgee.

Examples

## Illustrating the construction of a "fixed" local odds ratios structure 
## using the arthritis dataset. Here, we assume a uniform local odds ratios 
## structure equal to 2 for each time pair.

## Create the uniform local odds ratios structure.
lorterm <- matrixLOR(matrix(2,4,4))

## Create the LORterm argument.
lorterm <- c(lorterm)
lorterm <- matrix(c(lorterm),3,25,TRUE)

## Fit the marginal model.
data(arthritis)
fitmod.fixed <- ordLORgee(y~factor(trt)+factor(time)+factor(baseline),data=arthritis,
                id=id,repeated=time,LORstr="fixed",LORterm=lorterm)
fitmod.fixed