Abstract
This study describes the development and psychometric properties of the BOT-3 Movement Fundamentals Score (BOT-3-MFS). A nationally representative sample of individuals aged 4:0-24:11 (n = 1,360) were administered the BOT-3-MFS. Scores were analyzed to confirm that they followed expected developmental patterns and to evaluate internal consistency reliability. Test-retest stability and internal consistency were examined to establish reliability of the BOT-3-MFS. BOT-3-MFS scores in three clinical groups: developmental delay in the motor domain (n = 31), developmental coordination disorder (n = 31), and autism spectrum disorder (n = 39) were used to evaluate internal consistency in clinical populations, as well as explore known-group validity using matched control samples without motor impairments to test hypothesis-based group differences in performance on the BOT-3-MFS. The BOT-3-MFS demonstrated expected developmental patterns in the nationally representative sample of individuals aged 4:0-24:11. Internal consistency reliability ranged from .74-.84 in the normative sample and .82-.91 in the clinical groups. Test-retest stability was .84. All three clinical groups had significantly lower BOT-3-MFS compared to controls (p < .001). The standard difference in scores between clinical groups and controls ranged from moderate to large, with the largest standard difference in the developmental coordination disorder group (1.44). These findings suggest that the BOT-3-MFS score is a theoretically and research-based measure of fundamental movement skills that demonstrates expected developmental patterns in a normative sample, acceptable internal consistency reliability, high test-retest stability, and can be used to differentiate individuals with motor impairments from those without motor impairments.