This monte carlo study explored how four commonly
used test equating methods (linear, equipercentile,
and item response theory methods based on the
Rasch and three-parameter models) responded to tests
of different psychometric properties. The four methods
were applied to generated data sets where mean item
difficulty and discrimination as well as level of chance
scoring were manipulated. In all cases, examinee ability
was matched to the level of difficulty of the tests.
The results showed the Rasch model not to be very
robust to violations of the equal discrimination and
non-chance scoring assumptions. There were also
problems with the three-parameter model, but these
were due primarily to estimation and linking problems.
The recommended procedure for tests similar to
those studied is the equipercentile method.
Skaggs, Gary & Lissitz, Robert W. (1986). An exploration of the robustness of four test equating models. Applied Psychological Measurement, 10, 303-317. doi:10.1177/014662168601000308
Skaggs, Gary; Lissitz, Robert W..
An exploration of the robustness of four test equating models.
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