In 1964, Ben Wright, Bruce Choppin and Nargis Panchapakesan began development of Rasch measurement computer programs (RMT 10:2, 494-6). These followed Ben's pioneering factor analysis programs which ran on the University of Chicago's UNIVAC I computer in 1959.
The most successful of Ben's mainframe programs was BICAL (1976, with Ron Mead and later Susan Bell). This was written in FORTRAN IV to run on IBM 370 computers. It constructed measures from complete dichotomous data with a scoring key. It was distributed as source code which the user compiled. There are indications that it is still in use.
In 1983, Ben Wright was consultant to a research company, Mediax, of which John Michael Linacre was the Computer Sciences Manager. Mike had written his first computer program in 1965 for the University of Cambridge EDSAC II computer. Mediax was in need of analysis software for educational tests containing dichotomous and rating scale items. Further there were missing data. In a series of meetings starting on February 22, 1983, Ben and Mike decided to develop Rasch software, capable of analyzing those data. The software would run on the new business-capable IBM XT personal computer (released March 6, 1983) under the newly stable MS-DOS 2.1 operating system (October 1983).
Early in 1984 the Rasch computer program Microscale appeared. Ease of data entry and graphical output were important. So Microscale was designed as an add-on to the then widely-used Supercalc3 spreadsheet program. It was popular with test developers, particularly in the language area. A free version, "Student Microscale", was distributed with the free evaluation version of Supercalc3. A drawback of Supercalc3 was its limited dataset size. So "Professional Microscale" was produced as an add-on to the SYSTAT statistics package. Active distribution of Microscale came to an end in 1987.
Since the word "Microscale" was too long for an MS-DOS program name, users entered MSCALE at the DOS prompt to launch it. Ben Wright took this name and applied it to a rewrite of Microscale into Fortran to run on the University of Chicago, Department of Education, UNIX minicomputer. MSCALE appeared around 1987 (Wright, Matt Schulz, Richard Congdon, Mark Rossner, and various authors) and was designed to analyze dichotomies and rating scale data.
MSCALE was distributed as source code which users sometimes had trouble compiling correctly. It had a maximum dataset size which users were starting to exceed. Also personal computers were now becoming the researchers tool of choice. Consequently, Ben and Mike decided to produce a revised and enlarged version of MSCALE, called BIGSCALE, which began to be distributed in 1989 in compiled form for PC computers. Ben had another program, MSTEPS (Wright, Schulz, Congdon, Rossner), for partial credit items. Its functionality was incorporated into BIGSCALE and, with other enhancements, launched as BIGSTEPS in 1991.
In 1998, BIGSTEPS was rewritten for Windows and published as Winsteps. Since a feature of Winsteps is compatibility all the way back to MSCALE, some initially doubted that Winsteps really was a Windows-native program. An advantage of Windows, however, has been the ease with which new capabilities can be introduced into the program. Each time new capabilities have been introduced, users have found innovative uses for those capabilities, and made suggestions for further innovations, and so the range of its Rasch measurement applications is ever widening. Winsteps® is now published by Winsteps.com.
For comparison, BICAL had about 1,500 lines of FORTRAN code, MSCALE about 3,000 lines of FORTRAN code. Winsteps has about 65,000 lines of FORTRAN code, 6,000 lines of Visual Basic code, 40 lines of C++ code and also incorporates code modules provided by other software developers.
John Michael Linacre
Available Rasch software is listed at www.rasch.org/software.htm.
From Microscale to Winsteps: 20 years of Rasch Software development, Linacre J.M. Rasch Measurement Transactions, 2004, 17:4 p.958
|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: Using Rasch Models in the Social, Behavioral, and Health Sciences, George Engelhard, Jr.||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|
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