How much observation is enough? Refining the administration of SOPARC.
BACKGROUND
The Systematic Observation of Play and Recreation in Communities (SOPARC) was designed to estimate the number and characteristics of people using neighborhood parks by assessing them 4 times/day, 7 days/week. We tested whether this schedule was adequate and determined the minimum number of observations necessary to provide a robust estimate of park user characteristics and their physical activity levels.


METHODS
We conducted observations every hour for 14 hours per day during 1 summer and 1 autumn week in 10 urban neighborhood parks: 2 each in Los Angeles, CA; Albuquerque, NM; Columbus, OH; Durham, NC; and Philadelphia, PA. We counted park users by gender, age group, apparent race/ethnicity, and activity level. We used a standardized Cronbach's alpha and intraclass correlation coefficients to test the reliability of using fewer observations.


RESULTS
We observed 76,632 individuals, an average of 547/park/day (range 155-786). Interobserver reliability ranged from 0.80 to 0.99. Obtaining a robust estimate of park user characteristics and their physical activity required a schedule of 4 days/week, 4 times/day.


CONCLUSIONS
An abbreviated schedule of SOPARC was sufficient for estimating park use, park user characteristics, and physical activity. Applying these observation methods can augment physical activity surveillance.
Dept. of Health, RAND Corporation, Santa Monica, CA, USA.
Deborah A
DA
Cohen
Claude
C
Setodji
Kelly R
KR
Evenson
Phillip
P
Ward
Sandra
S
Lapham
Amy
A
Hillier
Thomas L
TL
McKenzie
D000367:Age Factors; D005260:Female; D006801:Humans; D015141:Los Angeles; D008297:Male; D009043:Motor Activity; D009516:New Mexico; D009657:North Carolina; D019370:Observation / Q000379:methods; D015588:Observer Variation; D009820:Ohio; D015143:Philadelphia; D010988:Play and Playthings; D011159:Population Surveillance / Q000379:methods*; D011633:Public Facilities / Q000706:statistics & numerical data*; D011998:Recreation; D012737:Sex Factors; D012959:Socioeconomic Factors; D014505:Urban Population