A report recently released by the Economic Studies program at the Brookings Institution delves into the complex process behind designing and scoring cognitive assessments. Author Brian Jacobs illuminates the difficult choices developers face when creating tests—and how those choices impact test results.
Understanding exam scores should be a simple enough task. A student is given a test, he answers a percentage of questions correctly, and he receives a score based on that percentage. Yet for modern cognitive assessments (think SAT, SBAC, and PARCC), the design and scoring processes are much more complicated.
Instead of simple fractions, these tests use complex statistical models to measure and score student achievement. These models—and other elements, such as test length—alter the distribution (or the spread) of reported test scores. Therefore, when creating a test, designers are responsible for making decisions regarding test length and scoring models that impact exam results and consequently affect future education policy.
Test designers can choose from a variety of statistical models to create a scoring system for a cognitive assessment. Each model distributes test scores in a different way, but the purpose behind each is the same: reduce the margin of error and provide a more accurate representation of...