Reliability of the Test of Gross Motor Development Third Edition Among Children with Developmental Coordination Disorder.

Aim: The Test of Gross Motor Development Third Edition (TGMD-3) is used to assess the development of fundamental movement skills in children from 3 to 10 years old. This study aimed to evaluate the intra-rater, inter-rater, and test-retest reliability and to determine the minimal detectable change (MDC) value of the TGMD-3 in children with developmental coordination disorder (DCD).

Methods: The TGMD-3 was administered to 20 children with DCD. The child's fundamental movement skills were recorded using a digital video camera. Reliability was assessed at two occasions by three raters using the generalizability theory.

Results: The TGMD-3 demonstrates good inter-rater reliability for the locomotor skills subscale, the ball skills subscale, and the total score (φ = 0.77 - 0.91), while the intra-rater reliability was even higher (φ = 0.94 - 0.97). Test-retest reliability was also shown to be good (φ = 0.79-0.93). The MDC₉₅ was determined to be 10 points.

Conclusion: This study provides evidence that the TGMD-3 is a reliable test when used to evaluate fundamental movement skills in children with DCD and suggests that an increase of 10 points represents a significant change in the motor function of a child with DCD.