Inter- and Intrarater Reliabilities of the Test of Gross Motor Development-Third Edition Among Experienced TGMD-2 Raters.

The purpose of this study was to examine the inter- and intrarater reliabilities of the Test of Gross Motor Development-third edition (TGMD-3). The TGMD-3 was administered to 10 typically developing children. Five raters with experience using the Test of Gross Motor Development-second edition (TGMD-2) scored the digitally recorded performances and then rescored the same performances after a period of 2 weeks. Intraclass correlation (ICC) was used to examine both inter- and intrarater reliabilities of scores. Interrater reliability for the total score, locomotor subscale, and ball skills subscale (ICC: 0.92-0.96) were all excellent, while individual skills (ICC: 0.51-0.93) had fair-to-excellent reliability. Intrarater reliability across all raters was also excellent (ICC: 0.77-0.98) but varied widely for individual raters (ICC: 0.28-1.00) including multiple examples of poor reliability. While raters experienced with the TGMD-2 can produce consistent scores for TGMD-3 total scale and subscales, additional training is needed to improve skill-specific reliability.