Publications & Resources

Comprehensive Educational Assessment for the States: The Duplex Design

Dec 1986

R. Darrell Bock and Robert Mislevy

State testing programs often attempt to provide annual information for use in student guidance and qualification, school and program evaluation, and for broad policy decisions. For these purposes, the programs have had to carry out several independent testing efforts based on different test instruments. In some cases, they have concurrently operated minimum competency testing, local achievement testing, and sampling assessment of curricular objectives. Because much the same content is covered in these tests, considerable duplication of costs and classroom time is necessarily involved.

With the development of a new type of assessment instrument, called a “duplex design,” these several functions of state testing programs can be served in a single test administration requiring no more time and resources than conventional student achievement testing. Employing a multiple-form instrument similar to that used in sampling assessment, the duplex design yields profiles of individual student achievement in main content areas, while producing from the same item responses a detailed evaluation of curricular objectives at the school, district, county and state levels. Thus, when used in a state-wide census of student attainment, the duplex design serves in one comprehensive assessment the needs of diverse parties to public education for information on student achievement, school performance, and system-wide progress in attaining educational goals.

An example of a duplex design for eighth-grade mathematics illustrates the construction of the assessment instrument. Various applications of such instruments, including linking of results from distinct duplex designs for purposes of between-state comparisons, show the potential of this type of testing program. A technical appendix outlines the statistical model by which attainment scores for individual students are estimated on the same scale as those measuring detailed curricular objectives at the school level.

Bock, R. D., & Mislevy, R. (1986). Comprehensive educational assessment for the states: The duplex design (CSE Report 262). Los Angeles: University of California, Los Angeles, Center for the Study of Evaluation.