plot.DIFtree {DIFtree} R Documentation

## Plotting of Item focussed Trees

### Description

Visualization of trees for items with DIF identified by item focussed recursive partitioning in dichotomous or polytomous items.

### Usage

## S3 method for class 'DIFtree'
plot(x, item, component = "intercept", cex.lines = 2,
cex.branches = 1, cex.coefs = 1, cex.main = 1, title = NULL, ...)


### Arguments

 x Object of class DIFtree item Number of the item, for which the tree shall be plotted component Component of the model for which the tree shall be plotted; can be "intercept" or "slope". For "Rasch" and "PCM" only one tree of item parameters is available for each DIF item and therefore component will be ignored. cex.lines Width of branches of the tree cex.branches Size of the labels of branches of the tree cex.coefs Size of coefficients in the terminal nodes of the tree cex.main Size of the title of the tree title Optional title, which is added to the tree; if title=NULL the title is the number of the plotted item. ... Further arguments passed to or from other methods

### Author(s)

Moritz Berger <moritz.berger@imbie.uni-bonn.de>
http://www.imbie.uni-bonn.de/personen/dr-moritz-berger/

### References

Berger, Moritz and Tutz, Gerhard (2016): Detection of Uniform and Non-Uniform Differential Item Functioning by Item Focussed Trees, Journal of Educational and Behavioral Statistics 41(6), 559-592.

Bollmann, Stella, Berger, Moritz & Tutz, Gerhard (2018): Item-Focussed Trees for the Detection of Differential Item Functioning in Partial Credit Models, Educational and Psychological Measurement 78(5), 781-804.

Tutz, Gerhard and Berger, Moritz (2016): Item focussed Trees for the Identification of Items in Differential Item Functioning, Psychometrika 81(3), 727-750.

DIFtree, predict.DIFtree, summary.DIFtree

### Examples

data(data_sim_Rasch)

Y <- data_sim_Rasch[,1]
X <- data_sim_Rasch[,-1]

## Not run:

mod <- DIFtree(Y=Y,X=X,model="Logistic",type="udif",alpha=0.05,nperm=1000,trace=TRUE)

plot(mod,item=1)

## End(Not run)


[Package DIFtree version 3.1.6 Index]