Elien Neimeijer

97 Procedure Data was collected between September 2017 and April 2018. Participation was on a voluntary basis. Participants were given oral and written information about the aim of the study and the process of data collection and storage. All participants and their le- gal guardians were informed that the data was confidential and anonymous, and that data was only reported on a living group-level. In addition, a multidisciplinary treatment team consisting of sociotherapist, psychologist, and psychiatrist determined whether a participant was able to give informed consent and to participate. Clients with severe and acute psychotic problems were excluded. All included participants, and if applicable their legal guardian, and a representative of the treatment team gave their oral and writ- ten consent. Ethics approval for this study was granted from the Ethics Committee of the Faculty of Social Sciences (ECSS) of the Radboud University (ECSW2017-3001-471). The questionnaires were conducted by trained (assistant) researchers specialised in working with individuals with MID-BIF. Most participants were assisted to complete the questionnaire by a (assistant) researcher who read the questions and answering cat- egories out loud and explained the questions to the participant if necessary. Alternative scripted phrases to enable questions to be explained in a different way were part of the training they received. If used, this would provide an additional way of checking partic- ipants’ understanding whilst preventing the (assistant) researcher from projecting their interpretation of the questions onto participants. The completed questionnaires were returned to the researcher (first author). Characteristics on participant level (gender, age, total IQ, legal status) and group level (security level, care intensity, group composi- tion, and ward size) were extracted from the records of the participants. Measures Group climate. Group climate was assessed with the Group Climate Instrument (Neimeijer, Roest, Van der Helm, & Didden, 2019; Van der Helm, Stams, & Van der Laan, 2011). This self-report measure consists of 29 items rated on a 5-point Likert type scale, ranging from 1 ( Not applicable ) to 5 ( Entirely applicable ). Each item belongs to one of the four scales of group climate: Support, Growth, Atmosphere, and Repression. The Support scale (11 items) assesses perceived support and responsiveness from group workers, such as listening to clients and taking their complaints seriously. An example