A Factor-Analytic Approach for Psychometric Properties of the Repetitive Behaviors Questionnaire-3 (RBQ-3) for Turkish Population.

Only 30 autistic people filled in the self-report form themselves, and they were all high school students. The authors could not recruit autistic adults in Türkiye, so the self-report form's structure was never checked in a large autistic sample, and whether it measures the same thing in autistic and non-autistic people was not tested at all. The sample used to set the self-report structure was 82% female university students, which the authors note does not match the sex mix usually seen in autism. In the sample where informants reported on autistic and neurotypical people, the two groups were very different: average age 11.49 years versus 25.27 years, and different education levels, sex mix and types of informant. The authors say these differences, not just the diagnosis, could explain the results and limit how far they generalise. To reach the four-area structure the team dropped item 7 from the self-report form and items 1 and 9 from the informant form, so this is not the same set of questions as the original English version and scores from the two are not directly comparable. The restricted interests area was below the usual reliability threshold in two of the samples (0.67 in the first sample and 0.55 in the autistic informant sample), which the authors attribute to how few items it contains. The team did not compare the questionnaire against another repetitive behaviour measure such as the RBS-R or GARS, so it is not known how its scores line up with tools already in use. Participants were recruited through the authors' professional networks and autism associations and answered online, so the samples are volunteers rather than a representative cross-section of Turkish families.

The authors declare no conflicts of interest. The text supplied names no funder or sponsor and describes no role for one in the design, analysis or write-up.

Do not read the higher informant scores for autistic people as the questionnaire detecting autism, or as a like-for-like comparison between groups. The autistic and neurotypical people in that sample were not alike: average age 11.49 versus 25.27 years, different education levels, different sex mix and different people filling in the form, and the authors say those differences could explain part of the gap.