descript {ltm}R Documentation

Descriptive Statistics for Response Matrices

Description

Computes the percentages of positive and negative responses for each item, as well as the pairwise associations between items (see Details for more info).

Usage

descript(data, n.print = 10, B = 1000)

Arguments

data a matrix or data.frame containing the manifest variables.
n.print numeric indicating the number of pairwise associations with the highest p-values to be printed.
B the B argument of chisq.test().

Details

Before an analysis with latent variable models, it is useful to inspect the data for evidence of positive correlations. In the case of binary data, this ad hoc check can be performed by constructing the 2 by 2 contingency tables for all possible pairs of items and examine the Chi-squared p-values. In case any expected frequencies are smaller than 5, simulate.p.value is turned to TRUE in chisq.test(), using B resamples.

Value

An object of class descript with components,

sample a numeric vector of length 2, with elements the number of items and the number of sample units.
perc a numeric matrix containing the percentages of positive and negative responses for each item.
items a numeric matrix containing the frequencies for the total scores.
pw.ass a matrix containing the p-values for the pairwise association between the items.
n.print the value of the n.print argument.
name the name of argument data.

Author(s)

Dimitris Rizopoulos dimitris.rizopoulos@med.kuleuven.be

Examples


## Descriptives for Wirs data:
descript(Wirs, 3)


[Package ltm version 0.4-1 Index]