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Detecting Intervention Effects Using a Multilevel Latent Transition Analysis with a Mixture IRT model. Sun-Joo CHO Allan COHEN Brian BOTTGE. Context.
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Detecting Intervention Effects Using a Multilevel Latent Transition Analysis with a Mixture IRT model Sun-Joo CHO Allan COHEN Brian BOTTGE
Context • If you are asked by national Department of Education to test the efficacy of a new instructional method which was designed to improve learning disabilities students’ performance. Students’ performance were measured in two time points. • People may concern that • (1) How much progress do student make? • (2) What’s the intervention effects?
(3) What does the progress depend on? (intervention, teacher or both) • (4) How do children’s response process change over time? • (5) Do student perform differently?
Measuring Change • CTT for measuring change • 1. repeated ANOVA or MANOVA: mean change of a total score as a manifest variable across time points • However, the assumption of sphericity (homogeneous and all correlation between any pair of measures equal) is often violated.
LTA-LCM • Latent Transition analysis with Latent Class Model • LTA-LCM assumes that there is no variability on the latent trait within classes. LCM LTA-LCM
LTA-MixIRTM • Latent transition model with a mixture response model Mixture Model LTA_MixIRTM
Mixture Proportion in teacher level latent class Mixture Proportion in individual level latent class Transition proportion IRT model Multilevel LTA-MixIRTM
Proportion of the population in group-level latent class • Proportion of the population in individual-level latent class at Time 1 • Transition proportion for t=2,…,T
Estimation • Assumption: Item parameters are invariant across time and across group-level latent class (item parameters are estimated using post-test data) • Anchor items (scale comparability among latent class?) • Mplus (TWOLEVEL MIXTURE)
Empirical Study Results • 310 students nested under 49 teachers answer 20 items at both pre-test and post-test occasion
(1) Multilevel 1PL ICC= 0.117 (pre-), 0.406 (post-) (2) Detection of Latent Classes A. Only one latent class at pre-test (very few students answer correctly) B. Two latent class at post-test for student-level C. Two latent class at post-test for teacher-level after the latent class at student level were determined
Comparison between multilevel LTA-MixIRTM and LTA-MixIRTM: students were clustered into four transition patterns in multilevel LTA MixIRTM whereas there was two in the LTA MixIRTM.
How do students’ response change over time? • On the post-test, 27.4% of the students were classified into student-level Class 2 (pattern 112 and 212). Higher transition proportion of pattern 212 indicate intervention effect.
How much progress? Teachers/intervention? • Pattern 212 has larger mean and large variance, indicating much progress.
In, Pattern 111 (pho=0.856), students tended to retain their relative positions. • In Pattern 211 (pho=0.004), little variability for these student on post-test.
Questions: • 1. How about item parameter recovery? • 2. Anchor item is necessary? • 3. Achilles’ heel in mixture model