Goal attainment scaling as a measure of change in infants with motor delays.

Goal attainment scaling (GAS) is an individualized criterion-referenced measure of change that has several unique features, compared with the behavioral objective, and five possible levels of attainment for each goal. The validity of GAS as a measure of motor change was investigated in 65 infants, 3 to 30 months of age, with motor delays. For each infant, two goals to be attained within a 6-month period of intervention were established. After the 6-month period, the mean GAS T-score of 55.4 was significantly higher than the expected mean of 50. This finding indicated that the infants' motor change exceeded the therapists' expectations. Neither the type nor the category of goal influenced the therapists' ability to select outcomes that the infants were capable of achieving. Because moderate and low correlations were found between GAS T-scores and Peabody gross motor and fine motor change scores, the two assessments appear to measure different aspects of motor development. Selected child, family, and program variables were examined as sources of bias in GAS T-scores. Motor delay was the only variable that biased GAS T-scores; infants who were less delayed had higher GAS T-scores. The results indicate that GAS was responsive to change in individualized motor goals and support the model of GAS as an idiosyncratic measure. The unique features of GAS offer advantages for measurement of motor change compared with the behavioral objective and norm-referenced developmental scales.