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By combining IRT and equalization, you can achieve a fair test no matter which test version you take. By operating the test over a long period of time, it is possible to create a collection of equalized test questions (item bank), and to conduct a highly fair test that is resistant to leakage of test questions.

IRT has a concept of test measurement accuracy, which is similar to the reliability of CTT. Measurement accuracy is an index that shows how much an individual's ability value varies on average when they take the same test repeatedly. IRT allows you to know detailed measurement accuracy for Candidate 's ability level. Even if it is equalized, if there is a large difference in difficulty between editions, there may be variations in the accuracy of this measurement. If we can create multiple test versions with equal measurement accuracy within a certain range, we can say that the test is more equal. Measurement accuracy in IRT is quantified by a curve on a number line called the amount of test information, so by setting appropriate standards and selecting questions from the item bank so that the curve is close, a fairer test version can be created. can be created.

また，1つの試験には複数の単元や出題分野と呼ばれるような試験問題のかたまりが設定されることが多いです。単に測定精度が等しいだけでなく，単元ごとに問題数のバランスも考慮して試験版を作成することも，公平な試験にとっては重要でしょう。試験の測定精度と単元ごとの問題数だけを満たすという条件では，常に同じような試験問題ばかりが出題されてしまい，最終的には試験問題のほとんどが受験者に対策されてしまうリスクがあります。したがって，測定精度と単元ごとの問題数に加えて，同じ問題がどれくらい使用されたか（露出率）を適切にコントロールしながら試験を運用することも重要です。プロメトリックではLinear On the Fly Testing (LOFT) と呼ばれる試験運用方法を提案しています。LOFTでは受験者が解答を始める瞬間に，解答すべき試験問題がランダムにアイテムバンクから選択されます。この際，測定精度・単元ごとの出題数・露出率，すべてのバランスの取れるように，最適化されたアルゴリズムが用いられています。

In recent years, a method called adaptive testing has become mainstream in CBT, which optimizes the questions asked depending on the test Candidate 's response situation.

At Prometric, we use highly reliable techniques such as question quality assessment, IRT, equalization, and LOFT to improve the quality of CBT exams and provide test analysis services that are fair to test Candidate and optimal for test administration organizations. I am.