Learn R Programming

logbin (version 1.0)

logbin.allref: Parameterization for CEM Algorithm

Description

A workhorse function for logbin, logbin.allref takes the formula and data for a log-link binomial GLM and produces a list of all parameterizations needed for the associated CEM algorithm.

Usage

logbin.allref(object, data = environment(object), mono, start = NULL)

Arguments

object
a model formula or a terms object for the addreg model.
data
a data frame created with model.frame. If another sort of object, model.frame is called first.
mono
a vector indicating which terms should be restricted to have a monotonically non-decreasing relationship with the outcome.
start
starting values for the parameters in the linear predictor.

Value

  • A list with components:
  • allrefa named list, with one component for each term in the model. Each component is itself a list, whose components are each of the parameterizations for that term. If start was specified, the first component for each term will correspond to the parameterization specified by start.
  • termsthe terms component of object.
  • datathe object passed into the data argument, or the result of calling model.frame with data.
  • monotonica named logical vector indicating which components of terms are restricted to be monotonically non-decreasing.
  • start.newa reparameterized version of start, corresponding to the first parameterization in allref. NULL if start was not supplied.

Details

In the CEM algorithms employed by logbin, the parameter space is partitioned into a collection of restricted parameter spaces (see Marschner (2014)). logbin.allref finds the list of possible parameterizations of each term in the model. If a term x has a TRUE value for is.factor(x), is.character(x) or is.logical(x), it is considered to be a categorical covariate. This has a parameterization for each level of the factor. Otherwise the covariate is considered to be continuous, in which case it has two possible parameterizations, relating to the minimum and maximum observed values. If a covariate is restricted to be monotonic via the mono argument, it has only one parameterization. logbin considers all possible combinations of the parameterizations of each covariate, and for each calls logbin.design to create the appropriate non-negative design matrix to be used in the EM algorithm.

References

Marschner, I.C. and A.C. Gillett (2012): "Relative risk regression: reliable and flexible methods for log-binomial models," Biostatistics, 13, 179--192. Marschner, I.C. (2014): "Combinatorial EM algorithms," Statistics and Computing, 24, 921--940.

See Also

logbin