PWEIGHT= person (case) weighting

PWEIGHT= allows for differential weighting of persons. The standard weights are 1 for all persons. To change the weighting of persons, specify IWEIGHT=.

 

PWEIGHT of 2 has the same effect on item estimation as putting the person and responses into the analysis twice. It does not change a person's responses scored 0-1 into responses scored 0-2. When PWEIGHT is 0 for a person, the measure and fit statistics are reported for the person, but the person does not influence the measures or fit statistics of the other persons or items. PWEIGHT= applies to everything except the dimensionality computations (Tables 23, 24) where PWEIGHT= is set to 1 and IWEIGHT= is set to 1 for all persons and items.

 

Raw score, count, and standard error of measurement reflect the absolute size of weights as well as their relative sizes. Measure, infit and outfit and correlations are sensitive only to relative weights. If you want the standard error of the final weight-based measure to approximate the S.E. of the unweighted measure, then ratio-adjust case weights so that the total of the weights is equal to the total number of independent observations.

 

PWEIGHT= file name

 

weights are in a text file of format:

(person entry number) (weight)

PWEIGHT = *

(person entry number) (weight)

....

*

in-line list of person-entry numbers and weights

PWEIGHT = $S2W3

PWEIGHT = $S2E4

weights in person labels which start at NAME1= using the column selection rules, e.g., starting in column S... with a width of W... or starting in column S and ending in column E.

This can be expanded, e.g, PWEIGHT = $S23W1+"."+$S25W2 places the columns next to each other (not added to each other)

PWEIGHT = $C2W3

PWEIGHT = $C2E4

weights in data records using the column selection rules. column1 of the data recode is C1. The format is starting in column C... with a width of W... or starting in column C... and ending in column E. The columns can be anywhere in the data record

 

Example 1:

In a sample of 20 respondents, person 1 is to be given a weight of 2.5, all other persons have a weight of 1.

 PWEIGHT=*

 1 2.5

 2-20 1

 *

 

A better weighting, which would make the reported item standard errors more realistic by maintaining the original total sum of weights at 20 , is:

 PWEIGHT=*

 1 2.33 ; 2.5 * 0.93

 2-20 0.93 ; the sum of all weights is 20.0

 *

+---------------------------------------------------------------------------------+

|ENTRY    RAW                   MODEL|   INFIT  |  OUTFIT  |PTMEA|     |          |

|NUMBER  SCORE  COUNT  MEASURE  S.E. |MNSQ  ZSTD|MNSQ  ZSTD|CORR.|WEIGH| KID      |

|------------------------------------+----------+----------+-----+-----+----------|

|     1      4     10   -1.20     .85| .65   -.9| .41    .3|  .82| 2.33| Richard M|

|     2      7     10    1.70    1.17| .18  -1.2| .10   -.4|  .94|  .93| Tracie  F|

|     3      7     10    1.70    1.17|2.04   1.2|1.32    .7|  .84|  .93| Walter  M|

 

Example 2:

The data records contain the weights in columns 16-18 of the record. The person label starts in column 15, so this is also column 2 of the person label

 NAME1 = 15  ; start of person label

 NAMELEN = 20  ; length of person label

 PWEIGHT= $S2W3 ; location in person label

  &END

 ...

 END NAMES

 10110110011001 0.5 Person A

 01001100011011 0.7 Person B

 ......

or

 NAME1 = 15  ; start of person label

 NAMELEN = 20  ; length of person label

 PWEIGHT= $C16W3 ; or $C16E18 ; column in data record also in person label

or

 NAME1 = 20  ; start of person label in column 20 excluding the person weight

 NAMELEN = 15  ; length of person label

 PWEIGHT= $C16W3 ; or $C16E18 ; column in data record, not in person label

 

Example 3:

Person 4 is a dummy case, to be given weight 0. The measure and fit statistics are reported for person 4, but person 4 does not influence the measures or fit statistics of the other persons or items.

 

 PWEIGHT=*

 4 0 ; Person 4 has weight 0, other persons have standard weight of 1.

 *


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