The FATS: An observational system for assessing physical activity in children and associated parent behavior

The psychometric properties of an observational measure (the FATS) of both physical activity and parent-child interactions related to physical activity were examined. Study 1 compared a normal weight and overweight male child assessed for 90 minutes utilizing the FATS. The overweight child was significantly less active and also received less parental encouragement to be active than the normal weight child. Study 2 demonstrated that a high degree of inter-rater reliability could be achieved and that the Composite Index of the FATS was significantly correlated with activity as assessed by a motion-activated physical activity recorder. The Composite Index was also positively correlated with the number of parental encouragements to be active and inversely related to the number of parental discouragements to be active and the child's relative weight. In Study 3, a generalizability analysis was conducted to assess the test-retest stability of the FATS. Results indicated that the FATS was a reasonably stable measure of physical activity and that acceptable stability and standard errors could be achieved with four measurement occasions. Implications of these results for future research are discussed.