Methodology
European researchers enter data in an underlying Database using a web application. The data are entered into the EDT in the different European Member States.
Government agencies from these Member States have formally granted access to the judicial documents for the case file research of violent extremists to one or two researchers in each Member State with the requisite expertise.
The data-entry takes place at the judicial organizations in which the judicial files are located. In the Netherlands this is the Public Prosecution Service and the Netherlands Institute of Forensic Psychiatry and Psychology (NIFP). Other Member States have their data-entry from their prison and probation organisations.
All qualitative information from judicial files is converted into quantitative codes, prior to being entered into the database, in order to enable quantitative analyses.
To minimize systematic bias in data collection across the participating organizations, methods of information exchange and data coding were established. As part of this procedure, an English Codebook with 16 domains and 400 items was developed in which descriptions for items and general coding rules are explained.
Additionally, involved researchers participate in a EDT coding training course, in which general coding instructions, explanations of the meaning of specific items, and illustrative examples are provided. As part of the training, researchers finished a couple of training cases, to allow for inter-rater reliability analyses (Alberda et al, 2021).