Research output per year
Research output per year
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Dive into the research topics where Letty Koopman is active. These topic labels come from the works of this person. Together they form a unique fingerprint.
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Collaborations and top research areas from the last five years
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Assumptions and Properties of Two-Level Nonparametric Item Response Theory Models
Koopman, L., Zijlstra, B. J. H. & van der Ark, L. A., Mar-2025, In: Psychometrika. 90, 1, p. 208-228 21 p.Research output: Contribution to journal › Article › Academic › peer-review
Open AccessFile3 Downloads (Pure) -
Investigating the Ordering Structure of Clustered Items Using Nonparametric Item Response Theory
Koopman, L. & Braeken, J., Apr-2025, In: Educational and Psychological Measurement. 85, 2, p. 336-356 21 p.Research output: Contribution to journal › Article › Academic › peer-review
Open AccessFile23 Downloads (Pure) -
Effect of Within-Group Dependency on Fit Statistics in Mokken Scale Analysis in the Presence of Two-Level Test Data
Koopman, L., 2023, Quantitative Psychology: The 87th Annual Meeting of the Psychometric Society, Bologna, Italy, 2022. Wiberg, M., Molenaar, D., González, J., Kim, J.-S. & Hwang, H. (eds.). Springer, p. 221-232 12 p. (Springer Proceedings in Mathematics & Statistics; vol. 422).Research output: Chapter in Book/Report/Conference proceeding › Chapter › Academic › peer-review
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Evaluating Model Fit in Two-Level Mokken Scale Analysis
Koopman, L., Zijlstra, B. J. H. & der Ark, L. A. V., 7-Aug-2023, In: Psych. 5, 3, p. 847-865 19 p.Research output: Contribution to journal › Article › Academic › peer-review
Open Access -
Maximum Augmented Empirical Likelihood Estimation of Categorical Marginal Models for Large Sparse Contingency Tables
van der Ark, L. A., Bergsma, W. P. & Koopman, L., Dec-2023, In: Psychometrika. 88, p. 1228-1248 21 p.Research output: Contribution to journal › Article › Academic › peer-review
Open Access
Activities
- 2 Academic presentation
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Investigating the ordering structure of clustered items using nonparametric item response theory
Koopman, L. (Speaker)
16-Jul-2024Activity: Talk and presentation › Academic presentation › Academic
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Stability and Scalability in Mokken Scale Analysis: Challenges of Small Samples and Deviant Items
Lortz, S. (Speaker), Post, W. (Contributor), Koopman, L. (Contributor) & Paap, M. (Contributor)
28-Nov-2024Activity: Talk and presentation › Academic presentation › Academic