Abstract: ObjectiveTo compare the responsiveness and precision between the 66 items version of Gross Motor Function Measure(GMFM-66) and 88 items version(GMFM-88).Methods173 children with cerebral palsy(male 126,female 47) who have received twice assessments were involved.All the second assessment were performed 3.8±4.3 months later.112 children received the third assessment 3.2±2.2 months after the second assessment.The effect size and relative precision between the GMFM-66 and GMFM-88 were analyzed.ResultsThe effect size of GMFM-66 between every two assessments was nearly the same as those of GMFM-88.The precision of GMFM-66 was not lower than that of GMFM-88.ConclusionThe interval-scale GMFM-66 has satisfying responsiveness and precision.It is more useful than GMFM-88 in measuring the treating effect of children with cerebral palsy.

Key words: cerebral palsy, gross motor, Gross Motor Function Measure(GMFM), effect size, relative precision