CAT’s Journey in Georgia. Introduction of GCAT. Decision Visit to CITO Tryouts First database of items (3P) Calibration, fine-tuning Algorithm, software Simulations, infrastructure Large-scale pre-test First GCAT. Fall 2010. November 2010. December 2010. December 2010.
Result: Tailor-made tests for each student with standardized scores
Approach: Measure a student’s ability in terms of how difficult an item she can solve.
Does little around here
Has 75% chance of solving a random item from around here
Does everything around here
The students ability and item parameters determine the probability of a correct response. In the two-parameter logistic model (2PL), this is done by the following function:
3 Random items
Choose next item (maximum information)
Check stopping conditions
Estimate ability, scale and display score, terminate.