check.monotonicity: Check of Monotonicity

Description

Returns a list (of class monotonicity.class) with results from the investigation of monotonicity (Junker and Sijtsma, 2000; Mokken, 1971; Molenaar and Sijtsma, 2000; Sijtsma and Molenaar, 2002).

Usage

check.monotonicity(X, minvi = 0.03, minsize = default.minsize)

Arguments

matrix or data frame of numeric data containing the responses of nrow(X) respondents to ncol(X) items. Missing values are not allowed

minvi

minimum size of a violation that is reported

minsize

minimum size of a rest score group. By default minsize = $N/10$ if $N \ge 500$; minsize = $N/5 if$ $250 \le N < 500$; and minsize = max$(N/3,50)$ if $N < 250$

Value

resultsA list with as many components as there are items. Each component itself is also a list containing the results of the check of monotonicity.
I.labelsThe item labels
HiThe item scalability coefficients Hi
mThe number of answer categories.

Details

The output is of class monotonicity.class, and is often numerous. Functions plot and summary can be used to summarize the output. See Van der Ark (2007) for an example.

References

Junker, B.W., and Sijtsma, K. (2000). Latent and manifest monotonicity in item response models. Applied Psychological Measurement, 24, 65-81. Mokken, R. J. (1971) A Theory and Procedure of Scale Analysis. Berlin, Germany: De Gruyter. Molenaar, I.W. and Sijtsma, K. (2000) User's Manual MSP5 for Windows [Software manual]. Groningen, The Netherlands: IEC ProGAMMA. Sijtsma, K, and Molenaar, I. W. (2002) Introduction to nonparametric item response theory. Thousand Oaks, CA: Sage. Van der Ark, L. A. (2007). Mokken scale analysis in R. Journal of Statistical Software. http://www.jstatsoft.org/v20/i11

Examples

Run this code

data(acl)
Communality <- acl[,1:10]
monotonicity.list <- check.monotonicity(Communality)
plot(monotonicity.list)
summary(monotonicity.list)

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