DEVELOPMENT AND EVALUATION OF AN OBSERVATION TOOL TO MEASURE PHYSICAL ACTIVITY IN OPEN ENVIRONMENTS

1002 Investigations of physical activity are hampered by lack of objective tools for quantifying activity in “open” environments, such as recreational settings. Measuring activity in these settings is complicated because the number of participants and their activity levels change frequently. This paper describes the instrument, System for Observing Play and Leisure Activity in Youth (SOPLAY). SOPLAY is based on momentary time sampling techniques in which systematic scans are made within pre-determined target areas. During a scan the activity of each individual is coded as Sedentary, Walking, or Very Active. Separate scans are made for females and males, and simultaneous entries are made for contextual variables. Because validity of the activity codes has been established through heart rate monitoring, energy expenditure can be estimated. The instrument permits comparisons to be made among different environments or within the same environment over time. Reliability data were collected during 14 days of field assessment by pairs of assessors who made independent observations. Data from 186 target areas in 14 schools were used in the realiability analysis. Interobserver agreements for contextual variables were 95% for area accessibility, 97% for usability, 93% for presence of supervision, 96% for presence of organized activity, and 88% for provision of equipment. To examine the reliability of activity measures made by different assessors, a series of intraclass correlations were computed. Correlations were high for counts of sedentary (R=.98) and walking girls (.95), although lower for very active girls (.76). For boys, correlations were high for sedentary (.98), walking (.98), and very active(.97) behavior. It was concluded that all interobserver agreements and intraclass correlations met acceptable criteria for reliable assessment. Utility of SOPLAY was established through 72 days of measurement in 24 middle schools.