winBugsRaggedArray {glmmBUGS}R Documentation

Ragged Arrays for multilevel models in BUGS

Description

Suitable for unbalanced data.

Usage

winBugsRaggedArray(data, effects = names(data)[-length(names(data))], covariates = NULL, observations = names(data)[length(names(data))], returnData = FALSE)

Arguments

data A data frame containing the response, covariates, and group membership.
effects A vector of character strings containing the grouping levels, from most general to most specific. Defaults to the column names of data, excluding the last column.
covariates A list with names corresponding to effects and each element being a vector of covariates applicable at that level
observations A character string giving the column of observations, or a vector where the first element is the observations and the remaning are offsets.
returnData If true, returns the re-ordered data frame as well as the data frame

Details

This funciton creates a list of data suitable for passing to the bugs function, suitable for implimentation as a ragged array. The output can be passed to getStartingValues to manipulate the output from glmmPQLstrings, and to restoreParams to restore the original parametrisation from bugs output.

Value

A list with the following components

Nxx The number of levels in the most general groupping
Syy Indexing sequences, one for each level. If yy is level n, level n+1 has elements Syy[1] to Syy[2]-1 belonging to the first category of level n.
Xyy Matrix or vector of covariates belonging to level yy
vector of observations.

Author(s)

Patrick Brown, patrick.brown@utoronto.ca

References

"Handling unbalanced datasets" in the "Tricks: Advanced Use of the BUGS Language" section of the bugs manual, at \url{http://mathstat.helsinki.fi/openbugs/data/Docu/Tricks.html#HandlingUnbalancedDatasets}

See Also

bugs

Examples

library(nlme)
data(Muscle)
muscleRagged = winBugsRaggedArray(Muscle, effects="Strip",  observations="conc",
  covariates=list(observations="length"))


[Package glmmBUGS version 1.5 Index]