textExposure control procedures in computerized adaptive testing (CAT) systems
protect item pools from being compromised, however, this impacts measurement
precision. Previous research indicates that exposure control procedures perform
differently for dichotomously scored versus polytomously scored CAT systems. For
dichotomously scored CATs, conditional selection procedures are often the optimal
choice, while randomization procedures perform best for polytomously scored CATs.
CAT systems modeled with testlet response theory have not been examined to
determine optimal exposure control procedures.
This dissertation examined various exposure control procedures in testletbased
CAT systems using the three-parameter logistic testlet response theory model
and the partial credit model. The exposure control procedures were the randomesque
procedure, the modified within .10 logits procedure, two levels of the progressive
restricted procedure, and two levels of the Sympson-Hetter procedure. Each of these
was compared to a baseline no exposure control procedure, maximum information.
The testlets were reading passages with six to ten multiple-choice items.
The CAT systems consisted of maximum information testlet selection
contingent on an exposure control procedure and content balancing for passage type
and the number of items per passage; expected a posteriori ability estimation; and a
fixed length stopping rule of seven testlets totaling fifty multiple-choice items.
Measurement precision and exposure rates were examined to evaluate the
effectiveness of the exposure control procedures for each measurement model.
The exposure control procedures yielded similar results for measurement
precision within the models. The exposure rates distinguished which exposure control
procedures were most effective. The Sympson-Hetter conditions, which are
conditional procedures, maintained the pre-specified maximum exposure rate, but
performed very poorly in terms of pool utilization. The randomization procedures,
randomesque and modified within .10 logits, yielded low maximum exposure rates,
but used only about 70% of the testlet pool. Surprisingly, the progressive restricted
procedure, which is a combination of both a conditional and randomization
procedure, yielded the best results in its ability to maintain and control the maximum
exposure rate and it used the entire testlet pool. The progressive restricted conditions
were the optimal procedures for both the partial credit CAT systems and the threeparameter
logistic testlet response theory CAT systems.Educational Psycholog