Data Storage on Rewritable Optical Disc

At Assessment Systems Inc (ASI), we analyze 500,000 real estate, insurance and allied health licensing and certification examinations a year. Each examinee record uses 1,000 bytes of computer disc space for exam identification, demographic data and response strings, using up 500 MB of disk space per year. Item analysis is performed on a 486 PC, often repeatedly as more examinee records arrive for a test form. Since we want to aggregate as many examinee records as possible for our analyses, this means having records for a year or more immediately available for speedy extraction of data subsets.

Computer tape allows voluminous data storage, but very slow access. Conventional PC hard disks can hold 600 MB, but would require us to purchase additional ones, as each filled up. Removable Bernoulli disks only store an impractically low 300 MB per disk.

Rewritable optical disk, though initially costly, provides random access, removable media of 640 MB per disc with transparent access through DOS. Now we can extract data from our archive files on the optical drive and format them for BIGSCALE in under 10 minutes.

Data Storage on Rewritable Optical Disc, L Newman … Rasch Measurement Transactions, 1992, 6:3 p. 240

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: 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
in Spanish: Análisis de Rasch para todos, Agustín Tristán Mediciones, Posicionamientos y Diagnósticos Competitivos, Juan Ramón Oreja Rodríguez

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