Dr Marike Polak is affiliated as an associate Professor to the Department of Psychology, Education and Child Studies (DPECS) at Erasmus University Rotterdam, the Netherlands. In this role she is involved in various research activities as a statistical expert. Furthermore, she carries out teaching activities concerning research methods & statistics education, as well as professional skills education. Moreover, she is chair of the Examination Board of Erasmus School of Social and Behavioral Sciences (ESSB). Her research interest are: psychometrics (with a special interest in validation methods for clinical diagnostic instruments, assessment of personality disorders, test development and individual differences); evidence-based research & validation; applied research in the field of (mental) health care. As a researcher she collaborates with other researchers both within as well as outside of the department. External collaborations include projects with mental health care professionals affiliated to the Developmental Profile foundation (*stichting Ontwikkelingsprofiel*), who focus on psychodynamic assessment of personality pathology. In addition, she has teamed up with researchers at Erasmus Medical Centre, where she is involved in various projects of the Department of Clinical Genetics, such as the assessment of informed decision-making. As an active member of the Dutch Committee on Tests and Testing ([COTAN][]) of the Dutch Association of Psychologists (*Nederlands Instituut van Psychologen, NIP*) she has been involved in drawing up the [Guidelines for the Use of Tests 2017][]. Lastly, she is a staff member of the Interuniversity Graduate School of Psychometrics and Sociometrics ([IOPS][]).   Research interests: psychometrics, evidence-based research & validation, applied research in the field of (mental) health care. [COTAN]: https://www.psynip.nl/actueel/themas/thema/psychologische-tests-cotan/ [Guidelines for the Use of Tests 2017]: https://www.psynip.nl/uw-beroep/cotan/cotan-beoordelingssysteem-ast-en-beroepscode/algemene-standaard-testgebruik-nip-2017/ [IOPS]: http://www.iops.nl/