Interrater reliability assessment using the Test of Gross Motor Development-2

Objectives: The aim was to examine interrater reliability of the object control subtest from the Test of Gross Motor Development-2 by live observation in a school field setting. Design:: Reliability Study - cross sectional. Methods: Raters were rated on their ability to agree on (1) the raw total for the six object control skills; (2) each skill performance and (3) the skill components. Agreement for the object control subtest and the individual skills was assessed by an intraclass correlation (ICC) and a kappa statistic assessed for skill component agreement. Results: A total of 37 children (65% girls) aged 4-8 years (M= 6.2, SD=0.8) were assessed in six skills by two raters; equating to 222 skill tests. Interrater reliability was excellent for the object control subset (ICC= 0.93), and for individual skills, highest for the dribble (ICC= 0.94) followed by strike (ICC= 0.85), overhand throw (ICC= 0.84), underhand roll (ICC= 0.82), kick (ICC= 0.80) and the catch (ICC= 0.71). The strike and the throw had more components with less agreement. Conclusions: Even though the overall subtest score and individual skill agreement was good, some skill components had lower agreement, suggesting these may be more problematic to assess. This may mean some skill components need to be specified differently in order to improve component reliability.