Examining rater effects of the TGMD-2 on children with intellectual disability.

The purpose of this study was to investigate rater effects on the TGMD-2 when it applied to children with intellectual disability. A total of 22 children with intellectual disabilities participated in this study. Children's performances in each of 12 subtests of the TGMD-2 were recorded via video and scored by three adapted physical activity specialists who have expertise in the TGMD-2. Two advanced measurement theories, Generalizability-theory (G-theory) and many-facet Rasch model (MFRM), were applied in data analyses. There were relatively large variances attributed to rater effects on the scores of the TGMD-2 awarded to children with intellectual disabilities. The severity of each rater significantly differed across all subtests of the TGMD-2. There was a set of biased ratings interacted with measurement conditions of the TGMD-2.