plot.iio.class: Plot iio.class objects

In vandenman/mokken: Conducts Mokken Scale Analysis

Description

S3 Method to plot objects of class iio.class. Graphic display of the checks of iio. One graph for each item plotting the estimated item response functions.

Usage

## S3 method for class 'iio.class'
plot(x, item.pairs = all.pairs, ci = TRUE, alpha = .05, 
       color = c("black", "blue"), transparancy = 20, ask = TRUE, ...)

Arguments

x	Object of class iio.class produced by check.iio.
item.pairs	vector containing the numbers of the item pairs for which the results are depicted graphically. For example, item.pairs = 1 prints the results for items 1 and 2, item.pairs = 2 prints the results for items 1 and 3, item.pairs = J prints the results for items 1 and $J$, and item.pairs = J+1 prints the results for items 2 and 3. Default the results for all item pairs are depicted.
ci	Boolean. If TRUE (default), then confidence envelops are plotted around IRFs.
alpha	Type of plotted (1 - alpha) confidence intervals. By default 95-percent confidence intervals are depicted
color	Color of the plotted curves and confidence envelops. Defaults are black for the first item and blue for the second item.
transparancy	Transparancy of the confidence intervals. Higher values result in more opaque colors for the confidence intervals.
ask	Boolean. If TRUE (default), then par("ask"=TRUE); i.e., a hard return between subsequent plots is required. If FALSE, then par("ask"=FALSE).
...	Optional graphical parameters will be ignored

Details

The plot function corresponds to method MIIO; each graph plots the estimated item response functions (item rest-score functions) for two items. For details of the method, see Ligtvoet et al. (2010, 2011); Sijtsma et al. (2012). For details of the confidence envelopes, see Van der Ark (2012b). For the implementation in R, see Van der Ark (2012a). For ask==FALSE, the default graphic device in R may only display the last graph.

Value

Returns a graph.

Author(s)

L. A. van der Ark [e-mail]

References

Ligtvoet, R., L. A. van der Ark, J. M. te Marvelde, and K. Sijtsma (2010). Investigating an invariant item ordering for polytomously scored items. Educational and Psychological Measurement, 70, 578-595.

Ligtvoet, R., L. A. van der Ark, W. P. Bergsma, and K. Sijtsma (2011). Polytomous latent scales for the investigation of the ordering of items. Psychometrika, 76, 200-216.

Sijtsma, K., R. R. Meijer, and L. A. van der Ark (2011). Mokken scale analysis as time goes by: An update for scaling practitioners. Personality and Individual Differences, 50, 31-37.

Van der Ark, L. A. (2012). New developments in Mokken scale analysis in R. Journal of Statistical Software, 48 (5), 1-27. http://www.jstatsoft.org/v20/i11

Van der Ark, L. A. (2014). Visualizing uncertainty of estimated response functions in nonparametric item response theory. In R. E. Millsap, L. A. van der Ark, D. Bolt, and C. M. Woods (Eds.), New developments in quantitative psychology (pp. 59-68). New York: Springer.

See Also

check.iio, summary.iio.class

Examples

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

vandenman/mokken documentation built on April 12, 2020, 4:06 a.m.