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V.E.C. (Letty) Koopman

Faculty of Social and Behavioural Sciences
Programme group: Methods and statistics

Visiting address
  • Nieuwe Achtergracht 127
Postal address
  • Postbus 15776
    1001 NG Amsterdam
Contact details
  • Profile

    Starting November 2016, Letty Koopman is a PhD student at the section of Methods and Statistics of the Research Institute of Child Development and Education. Her research project is called scaling methods for multilevel test data, in which multilevel test data refers to the fact that multiple raters score a subject. An example of such data is multiple pupils who scored their teacher. The project is funded with the Research Talent grant from the Netherlands Organisation for Scientific Research (NWO) and is supervised by prof. dr. L.A. van der Ark and dr. B.J.H. Zijlstra.


    Before starting her PhD position, Letty graduated from the Research Master Child Development and Education at the University of Amsterdam and the master Statistical Science of the Life and Behavioural Sciences at Leiden University.

  • Publications



    • Fukkink, R., Jilink, L., Op den Kelder, R., Zeijlmans, K., Bollen, I., & Koopman, L. (2019). The development of interaction skills in preservice teacher education: A mixed-methods study of Dutch pre-service teachers. Early Childhood Education Journal, 47(3), 321-329. [details]


    • Koopman, L., Zijlstra, B. J. H., & van der Ark, L. A. (2017). Weighted Guttman errors: Handling ties and two-level data. In L. A. van der Ark, M. Wiberg, S. A. Culpepper, J. A. Douglas, & W-C. Wang (Eds.), Quantitative psychology: The 81st Annual Meeting of the Psychometric Society, Asheville, North Carolina, 2016 (pp. 183-190). (Springer Proceedings in Mathematics & Statistics; Vol. 196). Springer. [details]


    • van der Ark, L. A., Korf, W., Peters, P., Chen, M., ten Hove, D., & Koopman, L. (2019). Onderzoek naar de verbetering van tests en vragenlijsten voor de pedagogische praktijk. In W. de Jong, J. Bekker, H. de Deckere, I. Schonewille, & L. van der Poel (Eds.), De belofte van de jeugd?!: Pedagogiek in de 21e eeuw (pp. 81-92). Uitgeverij SWP. [details]


    • van der Ark, L. A., Koopman, V. E. C., & Zijlstra, B. J. H. (2020). New advances in Mokken scale analysis. Paper presented at IMPS 2020 Virtual Conference, .


    • Koopman, V. E. C., Zijlstra, B. J. H., & van der Ark, L. A. (2018). Checking assumptions in two-level Mokken scale analysis. Paper presented at VIII European Congress of Methodology, Jena, Germany.


    • Koopman, V. E. C., de Rooij, M., Zijlstra, B. J. H., & van der Ark, L. A. (2017). Bias of two-level scalability coefficients and their standard errors. Paper presented at 82nd International Meeting of the Psychometric (IMPS) 2017, Zürich, Switzerland.


    • Koopman, L. (2017). Master's thesis prize Child Development and Education.

    Talk / presentation

    • van der Ark, A. (speaker), Koopman, L. (speaker) & Zijlstra, B. (speaker) (16-7-2020). Spotlight Talk: New Advances in Mokken Scale Analysis, IMPS 2020 Virtual Conference.
    • Koopman, L. (speaker), Zijlstra, B. (speaker) & van der Ark, A. (speaker) (27-2-2020). A two-step procedure for scaling multilevel data using Mokken's scalability coefficients, Psychoco 2020: International Workshop on Psychometric Computing, Dortmund.
    • Koopman, V. E. C. (speaker), Zijlstra, B. J. H. (speaker) & van der Ark, L. A. (speaker) (14-6-2018). Checking assumptions in two-level Mokken scale analysis, 33rd IOPS Summer Conference.


    • Koopman, V. E. C. (2020). A two-step, test-guided Mokken scale analysis, for nonclustered and clustered data.
    This list of publications is extracted from the UvA-Current Research Information System. Questions? Ask the library or the Pure staff of your faculty / institute. Log in to Pure to edit your publications. Log in to Personal Page Publication Selection tool to manage the visibility of your publications on this list.
  • Ancillary activities
    • No ancillary activities