Identifying and Quantifying the Unintended Variability in Common Systematic Observation Instruments to Measure Youth Physical Activity.
J Phys Act Health
; 15(9): 651-660, 2018 09 01.
Article
in En
| MEDLINE
| ID: mdl-29742990
ABSTRACT
BACKGROUND:
Direct observation protocols may introduce variability in physical activity estimates.METHODS:
Thirty-five physical education lessons were video recorded and coded using the System for Observing Fitness Instruction Time (SOFIT). A multistep process examined variability in moderate to vigorous physical activity (MVPA%; walking + vigorous/total scans). Initially, per-SOFIT protocol MVPA% (MVPA%SOFIT) estimates were produced for each lesson. Second, true MVPA% (mean MVPA% of all students using all observations, MVPA%true) estimates were calculated. Third, MVPA% (MVPA%perm) was calculated based on all permutations of students and observation order. Fourth, physical education lessons were divided into 2 groups with 5 lessons from each group randomly selected 10,000 times. Group MVPA%perm differences between the 10 selected lessons were compared with the MVPA%true difference between group 1 and group 2.RESULTS:
Across all lessons, 10,212,600 permutations were possible (average 291,789 combinations per lesson; range = 73,440-570,024). Across lessons, the average absolute difference between MVPA%true and MVPA%SOFIT estimates was ±4.8% (range = 0.1%-17.5%). Permutations, based on students selected and observation order, indicated that the mean range of MVPA%perm estimates was 41.6% within a lesson (range = 29.8%-55.9%). Differences in MVPA% estimates between the randomly selected groups of lessons varied by 32.0%.CONCLUSION:
MVPA% estimates from focal child observation should be interpreted with caution.Key words
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Physical Education and Training
/
Exercise
/
Walking
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Behavior Observation Techniques
Limits:
Child
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Female
/
Humans
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Male
Language:
En
Journal:
J Phys Act Health
Year:
2018
Document type:
Article