Education for all in action: Measuring teachers’ competences for inclusive education

regards to inclusive education. Furthermore, teachers’ scale-scores on this validated instru- ment are analysed in order to gain insight on teachers’ thinking about diversity in the classroom. Methodology Sample & respondents In order to allow for a process of trial and improvement as well as cross-validation, data was collected in two steps within Flanders (Belgium). In the first step, data was collected among pre-service teachers. Based on the exploratory factor analyses on this data, the survey was opti- mised and then tested again in the second step. During this second step, data from a new sam- ple consisting of in-service teachers was analysed using confirmatory factor analyses (for more information, see Plan of analysis). In the first step, data was collected among pre-service teach- ers in the fall of 2017 in a sample of teacher education institutions [45]. All teacher education institutions within a Flemish province were invited to participate. Seven of the eight institu- tions decided to participate in the study (participation rate = 87.5%), translating to a total number of 975 pre-service teachers filling out the online research instruments. Of these, 167 students were in training to become a nursery teacher, 155 were studying to become primary school teachers, whereas 143 and 433 were studying to become respectively lower or higher secondary school teachers. 75% of the sample were women, while the mean age was 27.38 with a range from 17 to 57. By the end of the survey, 647 students had provided valid answers, trans- lating to an attrition rate of 33.6%.

In the second step, data was collected with in-service teachers in the spring of 2018 [46]. All schools within one Flemish city were invited to participate. Of the 40 contacted schools, 28 participated in the study, translating to a participation rate of 70%. All teachers within each school were invited to fill out the online survey (N = 600). Of these, 213 were working in a pri- mary school, while 384 were situated in a secondary school (with 3 people providing no answer to this question). 73.2% of the sample were women, while the mean age was 41.02 with a range from 22 to 63. When comparing the data to previous descriptions of the Flemish teaching pop- ulation [47,48], we see a congruence for both age and gender divisions, indicating that no sys- tematic biases seem to have occurred. By the end of the survey, 520 respondents provided valid answers, translating to an attrition rate of 13.3%. Due to the anonymous and non-invasive nature of the research (being a voluntary, one- time participation of adults in survey-research on professional practice), no official approval by the ethics committee was sought. Following the European Code of Conduct for Research Integrity, all respondents agreed to a written informed consent stating that participation in the research was voluntary, that they could stop their participation at any moment, and that their answers would be processed anonymously. Instrument Item creation and selection. First, a pool of items was created by three researchers with expert knowledge on diversity in education. In order to maintain the goals of the DISCO-

instrument and reflect the central tenets of EfA, the following criteria were observed during this creation phase: (1) to mitigate the fragmentation of the EfA field and employ a broad defi- nition of diversity, items had to either be applicable to all children or refer to specific diversity groups in a balanced way; (2) items needed to explicitly measure a single practice or percep- tion; and (3) items needed to be relevant across multiple teaching contexts; this implied that items had to be recognisable for teachers across different teaching levels, including primary and secondary education; that items had to refer to actions that could be performed by all PLOS ONE Measuring teachers’ competences for inclusive education PLOS ONE | https://doi.org/10.1371/journal.pone.0291033 November 8, 2023 5 / 22