title: Physical activity surveillance in parks using direct observation.
abstract: BACKGROUND
  Primary features of observational public health surveillance instruments are that they are valid, can reliably estimate physical activity behaviors, and are useful across diverse geographic settings and seasons by different users. Previous studies have reported the validity and reliability of Systematic Observation of Play and Recreation in Communities (SOPARC) to estimate park and user characteristics. The purpose of this investigation was to establish the use of SOPARC as a surveillance instrument and to situate the findings from the study in the context of the previous literature.
  
  
  METHODS
  We collected data by using SOPARC for more than 3 years in 4 locations: Philadelphia, Pennsylvania; Columbus, Ohio; Chapel Hill/Durham, North Carolina; and Albuquerque, New Mexico during spring, summer, and autumn.
  
  
  RESULTS
  We observed a total of 35,990 park users with an overall observer reliability of 94% (range, 85%-99%) conducted on 15% of the observations. We monitored the proportion of park users engaging in moderate-to-vigorous physical activity (MVPA) and found marginal differences in MVPA by both city and season. Park users visited parks significantly more on weekend days than weekdays and visitation rates tended to be lower during summer than spring.
  
  
  CONCLUSIONS
  SOPARC is a highly reliable observation instrument that can be used to collect data across diverse geographic settings and seasons by different users and has potential as a surveillance system.
authors.affiliation: The Ohio State University, Department of Human Sciences; Room A256, 305 West 17th Ave, Columbus, OH 43210-1221. E-mail: ward.116@osu.edu.
authors.forename: Phillip
authors.initials: P
authors.lastname: Ward
authors.affiliation: San Diego State University, School of Exercise and Nutritional Sciences, San Diego, California.
authors.forename: Thomas L
authors.initials: TL
authors.lastname: McKenzie
authors.affiliation: RAND Corporation, Santa Monica California.
authors.forename: Deborah
authors.initials: D
authors.lastname: Cohen
authors.affiliation: University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
authors.forename: Kelly R
authors.initials: KR
authors.lastname: Evenson
authors.affiliation: RAND Corporation, Santa Monica California.
authors.forename: Daniela
authors.initials: D
authors.lastname: Golinelli
authors.affiliation: University of Pennsylvania, Philadelphia, Pennsylvania.
authors.forename: Amy
authors.initials: A
authors.lastname: Hillier
authors.affiliation: Behavioral Research Center of the Southwest/PIRE, Albuquerque, New Mexico.
authors.forename: Sandra C
authors.initials: SC
authors.lastname: Lapham
authors.affiliation: RAND Corporation, Santa Monica California.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Williamson
mesh_terms: D003625:Data Collection / Q000379:methods; D006293:Health Promotion / Q000458:organization & administration; D006302:Health Services Research; D006801:Humans; D009043:Motor Activity; D019370:Observation / Q000379:methods*; D011633:Public Facilities; D011998:Recreation; D012621:Seasons; D014481:United States; D014504:Urban Health