Student model. The student model (also called the proficiency
model and the competency model) is sometimes used as a simplified
representation of a test taker, showing the relevant KSAs that an
individual test taker might have. It contains the KSAs that are the
focus of measurement and the other characteristics of the test taker
that would affect the interpretation of test performance. After the
test taker responds to a task, the model can be updated indicating
the current estimate of the likelihood that the test taker has (or
lacks) the measured KSA(s). Sometimes, the student model (better
named the proficiency or competency model in this case) shows the
relevant KSAs that the population of test takers might have. In
addition to the KSAs and other attributes directly related to the test,
the student model may include a description of the intended test
takers in terms of what they generally know and are able to do, such
as familiarity with computers, need for accommodations, and so
forth. In sum, the student model includes the information about test
takers necessary to allow test developers to write tasks that are
appropriate for the intended population.
The student model is likely to contain more KSAs than are to be
included in the score report. For many tests there may be only a
single score summed over all of the measured KSAs. Even in tests
that report several subscores, there are likely to be more KSAs
measured in the test than are individually reflected in the score
report. To help with later work on the assembly model, test
developers find it useful to differentiate among the KSAs to be
reported separately and the KSAs that have been included in the
student model to support the reported information.