Research On Item Selection Criteria And Termination Rules Of Dual-objective CD-CAT

The computerized adaptive test（CAT）is a new test form based on the project reaction theory（IRT）and using the computer as a test tool.Ability values can be estimated by testing the psychological characteristics of the participant;the cognitive diagostic computerted adaptive test（CD-CAT）is based on the cognitive diagnostic theory（CDT）that presents the processing process of the participant in a specific field of knowledge,thus obtaining the participant’s cognitive status（knowledge state,KS）.In fact,the tester always hopes to get both the participant’s ability value and KS through a test,which can enrich the test results and improve the test efficiency.Therefore,the dual-objective cognitive diagnostic computer adaptive test（dual-objective CD-CAT）test presents both KS and ability values.However,no matter what CAT is,the item selection strategy and termination rules are important components of it,but also important factors affecting the test efficiency and test accuracy.By combing the literature on the dual-objective CD-CAT item selection strategy,It is found that no scholars have proposed the method of weighting the information indicators based on the item characteristics.Therefore,this paper first combines the item features with the information product approach to construct six new item selection indicators suitable for the dual-objective CD-CAT（D-WIPA,GDI-WIPA,OR-WIPA,A-WIPA,CDI-WIPA,ADI-WIPA）,and systematically examines the impact of these new item selection strategies on the item selection.Compared with the existing IPA and GINI selection strategies in the Monte Carlo simulation experiment,the results found that the newly proposed six weighted IPA selection strategies can significantly improve the estimation accuracy of KS in the short test,and in the longer test,the more obvious the new method in ability estimation accuracy.Overall,the OR-WIPA method highlights its advantages in KS and ability estimation accuracy.In addition,from the perspective of test security,most of the current two-objective CD-CAT item selection strategies have the problem of uneven item exposure.Based on this,the study proposed stratification item selection strategy,The item bank was stratified by using the 2PL discrimination index and the five CDT discrimination index（D,GDI,OR,a,CDI,ADI）,and comprehensively investigate the performance of different stratification strategies in maintaining the safety of the item bank.The results show that the stratification selection strategy can reduce the overlap rate and the square value and improve the exposure uniformity.Among them,the stratification by OR and D indicators can also ensure a high measurement accuracy on the basis of controlling the exposure uniformity of the items,which has obvious advantages.In addition,all current studies on dual-objective CD-CAT have adopted fixed-length test,and variable-length can improve test efficiency and reduce test pressure under the condition of ensuring test accuracy.For the first time,according to the posterior distribution of KS and ability,and combined with the characteristics of dual-objective CD-CAT,four variable-length termination rules suitable for dual-objective CD-CAT（GINIQM,PPRM,PPVM,PPQM）are constructed.and compare the difference of the four variable-length termination rules under the IPA selection strategy.It is found that the four variable-length termination rules have advantages and disadvantages,but they can significantly reduce test length and improve test efficiency while ensuring measurement accuracy,among which the best performance is GINIRM and PPQM.In general,the exploration of the two key components of the two-objective CD-CAT: item selection strategy and termination rule has obtained relatively satisfactory results.This result is also important for enriching and driving the development of dual-objective CD-CAT.At present,the research on item selection strategy is mainly single-source index,and the construction of multi-source index should be strengthened in the future research.The stratified item selection is instructive for the theory and practice of dual-objective CD-CAT.In addition,it is also important to investigate the performance of different binding methods in dual-target CD-CAT.And constructing the termination rule of the two-objective CD-CAT from the perspective of information is also an important research direction.