mokken (version 2.7.7)

plot.restscore.class: Plot restscore.class objects

Description

S3 Method to plot objects of class restscore.class. Graphic display of the checks of restscore. One graph for each item pair plotting the estimated item step response functions (ISRFs); confidence envelopes are optional. Intersections of the lines indicate violations of nonintersection,

Usage

## S3 method for class 'restscore.class':
plot(x, item.pairs = all.pairs, plot.ci = TRUE, color.ci = c("orange","yellow"), 
  alpha.ci = .05, ask = TRUE, ...)

Arguments

x

Object of class restscore.class produced by check.restscore.

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,

plot.ci

Boolean. If TRUE (default), then confidence envelops are plotted around ISRFs.

color.ci

Color of the plotted confidence envelops. Defaults are orange for the first item and yellow for the second item.

alpha.ci

Type of plotted (1 - alpha) confidence intervals. By default 95-percent confidence intervals are depicted

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

Value

• Returns a graph.

Details

For details of the method, see Molenaar and Sijtsma (2000) and Sijtsma and Molenaar (2002). For details of the confidence envelopes, see Van der Ark (2012) For the implementation in R, see Van der Ark (2007). For ask==FALSE, the default graphic device in R may only display the last graph. The default number of plots can increase rapidly for large numbers of items.

References

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 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.restscore, summary.restscore.class

Examples

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