sea.classbybreak {ldsa}R Documentation

Collect Descriptive Statistics for Entailment Models as a Function of Breakpoint

Description

Performs an enumeration of all response patterns associated with a series of error thresholds (as computed by sea.breakpoints), and returns a number of descriptive statistics for each. This can be useful as an initial step in identifying candidates for confirmatory latent class analysis.

Usage

sea.classbybreak(x, measure = c("rate", "z-score", "binom.p"), 
    max.classes = Inf, sea.table.precomp = NULL, 
    constructive = TRUE, ...)

Arguments

x a data.frame with observations on rows; missing data is permitted.
measure error measure to use; rate for absolute error rates, z-score for z-scores, or binom.p for p-values under an exact Binomial test.
max.classes stop processing after encountering a threshold which generates at least max.classes legal response patterns.
sea.table.precomp an object of class sea.table, computed on x (optional).
constructive logical; should sea.enumerate.constructive be used to perform the enumeration?
... additional arguments to sea.enumerate.

Details

sea.classbybreak calls sea.breakpoints to identify all error thresholds (based on measure) at which new entailments are identified. It then proceeds to enumerate the set of legal response patterns for each threshold (using sea.enumerate), retaining in each case the number of patterns (if any) and the fraction of x which is covered by the pattern set. This process continues until all breakpoints have been explored, or until a threshold is identified for which the number of legal patterns is greater than or equal to max.classes, at which point the algorithm terminates.

sea.classbybreak has a plot method, which can be useful for identifying thresholds with favorable size/error ratios. These can then be examined in greater detail, e.g. using sea.bclca.modelselect.

Value

A three-column matrix of class sea.classbybreak, whose columns contain (respectively):

ErrorThresh Error threshold used
NumClasses Number of legal response patterns at the specified error threshold
Coverage The fraction of rows of x which are covered by the set of legal response patterns

Author(s)

Carter T. Butts buttsc@uci.edu

See Also

sea.breakpoints, sea.entailment, sea.enumerate, sea.bclca.modelselect


[Package ldsa version 0.1-2 Index]