Apart from the Behrens and Langer checklist questions, three core criteria that were repeatedly found in almost all German checklists and in the validated checklists were also added as comprehensive general questions: openness, inter-subjective validity and reflexivity [ 10- 12].
Keeping this variety in mind and discovering that there was no standard checklist for performing meta-synthesis, the research team selected the checklists of CASP, Cohen & Crabtree, and the German checklists of Steinke and of Behrens and Langer in a narrow stage-by-stage selection [ 23, 26- 28].
In wave 3, a German language checklist and, for bilingual children, an additional Turkish or Russian language checklist (versions of the well-known MacArthur Communicative Development Inventory (CDI); Fenson et al. 1993) was introduced.
German ADHD symptom checklist (Fremdbeurteilungsbogen für Aufmerksamkeitsdefizit-Hyperaktivitätsstörung, FBB-ADHD) [ 5, 10, 11 ].
Teachers and parents completed the German ADHD Symptom Checklist (Fremdbeurteilungsbogen für Aufmerksamkeitsdefizit-Hyperaktivitätsstörung, FBB-ADHD) [ 9, 16] for each visit.
The outcome variable used to describe the response trajectory was the mean symptom score, calculated using the German ADHD Symptom Checklist (Fremdbeurteilungsbogen für Aufmerksamkeitsdefizit-Hyperaktivitätsstörung [FBB-ADHD]), which is part of the German Diagnostic System for Mental Disorders in Children and Adolescents (DISYPS) [ 37].
In addition to a short sociodemographic questionnaire, participants will fill in an electronic version of the following questionnaires: The symptom checklist (German version) is a measure of general psychopathological symptom severity and has been widely used in studies and clinical practice.
Measures of ADHD symptoms and quality of life were obtained using the CGI S scale, the German ADHD symptom checklist (Fremdbeurteilungsbogen für Aufmerksamkeitsdefizit Hyperaktivitätsstörung [FBB-ADHD]; rated by teachers and parents), DAYAS (rated by teachers and parents) and a HRQoL questionnaire (Kinder Lebensqualitätsfragebogen [KINDL]) [ 49].
Problem behaviour during homework was assessed using the Homework Problem Checklist (HPC, German version) [ 8 ].
The German version of the Symptom Checklist by Derogatis [ 39] was also used to measure phobia.
