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gRc (version 0.5.1)

step: Stepwise model selection in RCOX models

Description

These allow for stepwise model selection in RCOX models by. Model expansion (i.e. forward selection) is obtained by adding edge colour classes and by splitting edge/vertex colour classes. Model reduction (i.e. backward selection) is obtained by dropping edge colour classes and by joining edge/vertex colour classes.

Value

Either NULL or a new RCOX model.

Arguments

object

An RCOX model, an object of class RCOX

scope

A set (list) of items (edge colour classes or vertex colour classes) to be considered. If missing, then all items are considered.

criterion

Either "aic" (the default), "bic" or "test" (for significance test)

type

Either "ecc" for edge colour classes or "vcc" for vertex colour classes.

k

The multiple of the number of degrees of freedom used for the penalty when criterion is "aic". Ignored when criterion is "bic" or "test". Only k = 2 gives the genuine AIC.

steps

The maximum number of steps to be considered. The default is 1000 (essentially as many as required). It is typically used to stop the process early

stat

Either "wald" for a Wald statistic or "dev" for a deviance statistic.

alpha

Critical value if 'criterion' is "test". If criterion is "aic" or "bic", the critical value is 0.

headlong

If TRUE then at each step the first encountered edge that may be removed/added according to the current criterion is done so.

random

If TRUE, then the edges are examined in random order

details

Control the amount of output created.

trace

For debugging purposes

...

Additional arguments, currently not used.

Author

Søren Højsgaard, sorenh@math.aau.dk

See Also

split1 join1 add1.rcox drop1.rcox comparecc