Example 17: Rack, stack, contrasts

Comparisons of measures at two time-points or in two situations can become complicated. Example 12 illustrates a straightforward situation. It uses the 13 motor items of the FIM®. This example uses the 18 items of the FIM, 13 motor and 5 cognitive, at two time points. There is a 7-level rating scale that is intended to operate in the same way across all items.

 

In exam17s.txt, the data have been stacked. The items are modeled to maintain their difficulties across the two time points, and the 52 patients are entered twice, once at admission to rehabilitation and once at discharge from it, so there 104 data records. Changes in patient independence can be identified by cross-plotting the admission and discharge measures for each patient, as in Example 12. This can be done by using the Plots menu to plot the measures against themselves, and then, in Excel, pasting the discharge measures over the top of the admission measures for the y-axis.

 

In exam17r.txt, the data have been racked. The persons are modeled to maintain their abilities across the two time points, and the 18 FIM items are entered twice, once at admission to rehabilitation and once at discharge from it, so there 36 items. Average changes in patient performance on individual items can be identified by cross-plotting the admission and discharge measures for each item. This can be done by using the Plots menu to plot the measures against themselves, and then, in Excel, pasting the discharge measures over the top of the admission measures for the y-axis.

 

A further feature is the contrasts in the Principal Components Analysis of Residuals, Tables 23 and 24. The 13 motor items and 5 cognitive items are probing different aspects of patient independence. Do they function as one variable in this sample? See Principal components/contrast. Patients also have different impairments. Are their measures comparable? See Differential Item Function.

 

; This control file is EXAM17S.TXT

TITLE='Example 17S: 18-item FIM control file: stacked admission then discharge'

ITEM1=1  ; Responses start in column 7

NI=18  ; 13 motor items + 5 cognitive items

NAME1=20 ; start of person label

; variables in person label

@SETTING=$S1W1 ; setting: A=Admission, D=Discharge

@SEX=$S3W1 ; Gender: 1=Male, 2=Female

@IGC=$S5W2 ; Impairment Group Code: 8=Orthopedic, 9=Cardiac, 10=Pulmonary, 11=Burns, 12=Congenital, 13=Other

@ID=$S8W2 ; Patient sequence number

 

; variables in item label

@SUBTEST=$S1W1  ; subtest: M=Motor, C=Cognitive

@ILETTER=$S3W1 ; code letter of item

 

CODES=1234567 ; 7 level rating scale

CLFILE=* ; Defines the rating scale

1 0% Independent

2 25% Independent

3 50% Independent

4 75% Independent

5 Supervision

6 Device

7 Independent

*

&END

M A. EATING

....

C R. MEMORY

END NAMES

334412312331123112 A 1  8  1

432322442223134444 A 2  8  2

....

 

; This control file is EXAM17R.TXT

TITLE='Example 17: 18-item FIM control file: racked admission and discharge'

ITEM1=1  ; Responses start in column 7

NI=37  ; 13 motor items + 5 cognitive items: admission and discharge

NAME1=39 ; start of person label

 

; variables in person label

@SEX=$S1W1 ; Gender: 1=Male, 2=Female

@IGC=$S3W2 ; Impairment Group Code: 8=Orthopedic, 9=Cardiac, 10=Pulmonary, 11=Burns, 12=Congenital, 13=Other

@ID=$S5W2 ; Patient sequ. number

 

; variable in item label

@SETTING=$S1W1 ; setting: A=Admission, D=Discharge

@SUBTEST=$S3W1  ; subtest: M=Motor, C=Cognitive

@ILETTER=$S5W1 ; code letter of item

 

CODES=1234567 ; 7 level rating scale

CLFILE=* ; Defines the rating scale

1 0% Independent

2 25% Independent

3 50% Independent

4 75% Independent

5 Supervision

6 Device

7 Independent

*

&END

A M A. EATING

....

A C R. MEMORY

-      Blank for ease of seeing

D M A. EATING

....

D C R. MEMORY

END NAMES

334412312331123112 554535546665345545 1  8  1

432322442223134444 777677777666567777 2  8  2

....


Help for Winsteps Rasch Measurement Software: www.winsteps.com. Author: John Michael Linacre

For more information, contact info@winsteps.com or use the Contact Form
 

Facets Rasch measurement software. Buy for $149. & site licenses. Freeware student/evaluation download
Winsteps Rasch measurement software. Buy for $149. & site licenses. Freeware student/evaluation download

State-of-the-art : single-user and site licenses : free student/evaluation versions : download immediately : instructional PDFs : user forum : assistance by email : bugs fixed fast : free update eligibility : backwards compatible : money back if not satisfied
 
Rasch, Winsteps, Facets online Tutorials

 

Forum Rasch Measurement Forum to discuss any Rasch-related topic

Click here to add your email address to the Winsteps and Facets email list for notifications.

Click here to ask a question or make a suggestion about Winsteps and Facets software.

Rasch Publications
Rasch Measurement Transactions (free, online) Rasch Measurement research papers (free, online) Probabilistic Models for Some Intelligence and Attainment Tests, Georg Rasch Applying the Rasch Model 3rd. Ed., Bond & Fox Best Test Design, Wright & Stone
Rating Scale Analysis, Wright & Masters Introduction to Rasch Measurement, E. Smith & R. Smith Introduction to Many-Facet Rasch Measurement, Thomas Eckes Invariant Measurement with Raters and Rating Scales: Rasch Models for Rater-Mediated Assessments, George Engelhard, Jr. & Stefanie Wind Statistical Analyses for Language Testers, Rita Green
Rasch Models: Foundations, Recent Developments, and Applications, Fischer & Molenaar Journal of Applied Measurement Rasch models for measurement, David Andrich Constructing Measures, Mark Wilson Rasch Analysis in the Human Sciences, Boone, Stave, Yale
in Spanish: Análisis de Rasch para todos, Agustín Tristán Mediciones, Posicionamientos y Diagnósticos Competitivos, Juan Ramón Oreja Rodríguez
Winsteps Tutorials Facets Tutorials Rasch Discussion Groups

 


 

 
Coming Rasch-related Events
Jan. 5 - Feb. 2, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com
Jan. 10-16, 2018, Wed.-Tues. In-person workshop: Advanced Course in Rasch Measurement Theory and the application of RUMM2030, Perth, Australia (D. Andrich), Announcement
Jan. 17-19, 2018, Wed.-Fri. Rasch Conference: Seventh International Conference on Probabilistic Models for Measurement, Matilda Bay Club, Perth, Australia, Website
Jan. 22-24, 2018, Mon-Wed. In-person workshop: Rasch Measurement for Everybody en español (A. Tristan, Winsteps), San Luis Potosi, Mexico. www.ieia.com.mx
April 10-12, 2018, Tues.-Thurs. Rasch Conference: IOMW, New York, NY, www.iomw.org
April 13-17, 2018, Fri.-Tues. AERA, New York, NY, www.aera.net
May 22 - 24, 2018, Tues.-Thur. EALTA 2018 pre-conference workshop (Introduction to Rasch measurement using WINSTEPS and FACETS, Thomas Eckes & Frank Weiss-Motz), https://ealta2018.testdaf.de
May 25 - June 22, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com
June 27 - 29, 2018, Wed.-Fri. Measurement at the Crossroads: History, philosophy and sociology of measurement, Paris, France., https://measurement2018.sciencesconf.org
June 29 - July 27, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Further Topics (E. Smith, Winsteps), www.statistics.com
July 25 - July 27, 2018, Wed.-Fri. Pacific-Rim Objective Measurement Symposium (PROMS), (Preconference workshops July 23-24, 2018) Fudan University, Shanghai, China "Applying Rasch Measurement in Language Assessment and across the Human Sciences" www.promsociety.org
Aug. 10 - Sept. 7, 2018, Fri.-Fri. On-line workshop: Many-Facet Rasch Measurement (E. Smith, Facets), www.statistics.com
Sept. 3 - 6, 2018, Mon.-Thurs. IMEKO World Congress, Belfast, Northern Ireland www.imeko2018.org
Oct. 12 - Nov. 9, 2018, Fri.-Fri. On-line workshop: Practical Rasch Measurement - Core Topics (E. Smith, Winsteps), www.statistics.com

 

 

Our current URL is www.winsteps.com

Winsteps® is a registered trademark
 


 
Concerned about aches, pains, youthfulness? Mike and Jenny suggest Liquid Biocell