WrightMap - R Statistics

R Statistics WrightMap produced from the Winsteps "Plots" menu using Example0.txt and the default values for the Winsteps-produced WrightMap. WrightMap is courtesy of   Torres Irribarra, D. & Freund, R. (2014). Wright Map: IRT item-person map with ConQuest integration.  Available at https://github.com/david-ti/wrightmap.

 

 

To save plot to Desktop, right-click on plot or, at the R Statistics prompt,  > dev.print(pdf, 'filename.pdf')

 

 

With the Winsteps WrightMap interface, no knowledge or R action is required. The WrightMap is produced like this:

1.Install R Statistics (once only)

2.Launch Winsteps

3.Do an analysis

4.Winsteps Plots menu, "Wright Map"

5.Let's go with the defaults: click on "WrightMap (Save)" - One Click!

6.R Statistics launches automatically. (No action needed by you.)

7. WrightMap displays. (No action needed by you.)

8.To save the WrightMap to your Desktop, right-click on it, or at the R Statistics prompt,  > dev.print(pdf, 'filename.pdf')

9.When finished with R: click on the R-window top-right close box.

 

Notes:

1.You can have several plots open at once. Each has a new instance of R.

2.Andrich thresholds: they are shown at their numerical value, whatever their ordering, except for thresholds for unobserved categories. These should be at infinity, but are shown at the item difficulty.

 

WrightMap Plot Control

WrightMap command - see

WrightMap/WrightMap.pdf

Purpose

Top:



Main title

main.title =

Main title at the top of the Wright Map

Default: TITLE=

Left-side (person.side) Persons

Right-side (item.side) Items

wrightMap (thetas, thresholds,

Person distributions on left side.

Item columns on right side of Wright Map

Left-side (person.side) Items

Right-side (item.side) Persons

wrightMap (thresholds, thetas,

Item distributions on left side.

Person columns on right side of Wright Map

1st Column:

person.side

Left-side of Wright Map

Left-side title

axis.persons =

Subtitle for left side

Default: PERSON=/ITEM= and name of statistic

Left-side: measures


the histograms on the left-side are of measures.

Fit: Outfit mean-square

Outfit standardized

Infit mean-squares

Infit standardized


the histograms on the left-side are of fit statistics

Left-side person/item statistic distn

first column of thetas/thresholds

Are the all the person/items the first distribution on the left side

Left-side group statistic distns

more columns of thetas/thresholds

Are there distributions on the left side for person/item groups

Group code in person/item labels

dim.names =

Codes in person/item labels identifying person/item groups

Colored?

dim.color =

Are the person/item distributions colored?

Left-side shown as: Histogram

person.side = personHist

Show person/item distributions as historgrams.  Distributions with only one person/item are increased to two for display purposes only.

Continuous density

person.side = personDens

Show person/item distributions as smoothed curves.  Distributions with only one person/item are increased to two for display purposes only.

1st Column:

item.side

Right-side of Wright Map

Right-side shown as

In columns (Modern)

item.side = itemModern

each item/person has a column

Compressed (Classic)

item.side = itemClassic

items/persons compressed into one column

Histogram

item.side = itemHist

items/persons shown as a histogram

Display item/person labels

label.items=

item/person labels displayed below columns

Entry number


include item/person entry number in column label

Label


include item/person label in column label

Full label


include as much of item/person label as possible

Label field


include this part of  item/person label

x-axis ticks

label.items.ticks =

show a tick on the x-axis for each item/person

Show vertical lines

vertLines =

connect plotted threshold values with a faint line for eahc item/person

Show threshold labels

show.thr.lab =

label the item/person thresholds with their threshold numbers

Threshold symbols:

show.thr.sym=

mark the item/persons threshold with symbols

(symbol box)

thr.sym.pch =

symbol(s) to use. Available symbols, 1-25, are shown. For instance, 3, 4

Colored?

thr.sym.col.fg=

thr.lab.col=

threshold labels and symbols are colored

2nd Column:

item.side

Right-side of Wright Map

Right-side title

axis.items =

Subtitle for right side

Default: ITEM=/PERSON= and ordering

Right-side size 0.0 to 1.0

item.prop =

right-side proportion of the whole plot

Right-side measures


the display on the right-side is of measures

Add item/person measures

thresholds

item/person measures are added to the threshold values

Measure-relative values

Andrich thresholds

thresholds

threshold values are Andrich thresholds relative to item/person measures

Thurstonian thresholds

thresholds

threshold values are Thurstonian thresholds relative to item/person measures

Half-point thresholds

thresholds

threshold values are Half-point thresholds relative to item/person measures

Maximum probability full-point

thresholds

threshold values are points of maximum probability for the categories relative to item/person measures, where observed score on the item = the expected score, corrected for extreme categories

None: Measures only

thresholds

threshold values are not added to the item/person measures

Outfit mean-square

Outfit standardized

Infit mean-squares

Infit standardized


the display on the right-side is of fit statistics

(symbol box)

thr.sym.pch =

symbol(s) to use. Available symbols, 1-25, are shown. For instance, 3, 4

3rd Column:

item.side

Right-side of Wright Map

Sort order:

Ascending

Descening

thresholds

order of item/person columns

Sort measures by

Entry number

Measure

Alphabetically

Fit: Outfit mean-square

Outfit standardized

Infit mean-squares

Infit standardized

thresholds

values to use when ordering the item/person columns.

Alphabetically: see right-side Label

 

y-axis label

axis.logits =

Title of y-axis, such as "Logits"

Default: ITEM=/PERSON= and name of statistic

y-axis range from: (Low) to: (High)

min.l=     max.l=

Sets the extremes of the y-axis. Blank or non-numeric for the default values

y-axis on right, y-axis in center, no y-axis

show.axis.logits = "L", "R" or "N"

placement of y-axis on plot

4th Column:

person.side

Left-side of Wright Map

Left-side group (dimension) labels position: Above, Below, Left, Right

dim.lab.side =

Placement of the labels for the left-side histograms

Left-side group (dimension) labels

Adjust 0.0 to 1.0

dim.lab.adj =

Adjust position of labels for the left-side histograms: 0.5 = middle position, 0.0 = left position, 1.0 = right position

Left-side group (dimension) labels

Size 0.1 upwards

dim.lab.cex =

Font size of labels for left-side histograms. 0.6 is the default.

4th Column:

item.side

Right-side of Wright Map

Right-side column labels

Size 0.1 upwards

label.items.cex =

Font size of labels for right-side histograms. 0.6 is the default.

Threshold label position:

Alternate, Above, Below, Left, Right

thr.lab.pos =

Placement of the labels for the right-side thresholds

Threshold labels

Size 0.1 upwards

thr.lab.cex =

Font size of labels for thresholds. 0.6 is the default.

Threshold labels

Font: Plain, Bold, Italic, Bold Italic

thr.lab.font =

Font style of labels for thresholds. Plain is the default.

Threshold symbols

Size 0.1 upwards

thr.sym.cex =

Font size of symbols for thresholds. 0.6 is the default.

Vertical lines between thresholds

Width

thr.sym.lwd =

Width of vertical light-grey lines between thresholds.

Push buttons:



Wright Map (Save)

wrightMap(....)

 

To save the displayed plot, right-click in the plot window.

launches R Statistics WrightMap function and saves the settings in the Dialog box.

Exit-No Save


Closes the Dialog Box without saving any changed settings since the last Wright Map output

Save and Exit


Saves the settings and closes the Dialog Box.

Help


Displays this page

Reset to defaults


Sets all WrightMap settings to their default values

Reset sizes to defaults


Sets sizes of fonts, symbols and lines to their default values

 

Notes:

1. WrightMap requires that R Statistics is installed: cran.rstudio.com/bin/windows/base/

 

2. The WrightMap will be slow to display the first time because the required R Statistics packages will be installed automatically. WrightMaps are never fast to display.

 

3. If your WrightMap appears wrong, please allow Winsteps to install the most recent relevant version of the WrightMap package. In your R window:

> remove.packages("WrightMap")

then the correct package will be installed automatically by Winsteps when you launch the next WrightMap.

 

5. After viewing the WrightMap, you can use all the R Statistics functions, or close the R windows. Respond "No" if there is a "Save workspace" message.

 

6. To change the titles, etc.

Make the plot in R, then do > ls() to see where all the labels etc. are stored:

 

> ls()

[1] "colors" "dimnames" "labels" "q" "quit"

[6] "thetas" "thresh" "threshlabels" "titles" "zero"

 

for the item labels:

> labels

[1] "1. Watch" "2. Read b" "3. Read b" "4. Watch" "5. Find b" "6. Look u"

[7] "7. Watch" "8. Look i" "9. Learn" "10. Liste" "11. Find" "12. Go to"

[13] "13. Grow" "14. Look" "15. Read" "16. Make" "17. Watch" "18. Go on"

[19] "19. Go to" "20. Watch" "21. Watch" "22. Find" "23. Watch" "24. Find"

[25] "25. Talk"

> labels <- c("label1", "label2", ........, "labelast")

 

You may want to remove the x-axis label:

> titles

TITLES

1 LIKING FOR SCIENCE (Wright & Masters p.18)

2 KID Measure

3 ACT in Entry order ascending <- this will overlay longer labels

4 ACT Measure (Andrich Thresholds)

 

You can change the left-hand column headings "dimnames"

dimnames <- c("heading 1", "heading 2", "heading 3")

 

Then copy the very long line on the R screen starting "wrightMap ...."

and paste it at the >

to make the plot again

 

Example 2: WrightMap of groups of item difficulties with person measures ascending.

 

 

 


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