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Table 3 Adolescents characteristic with no accelerometer data compared to adolescents with valid accelerometer data, n = 1337 (Initial N = 1296)

From: Accelerometer data reduction in adolescents: effects on sample retention and bias

  No accelerometer data* Valid accelerometer data** p-value
Sex, % (n = 1337) (n = 205) (n = 1132) 0.011
Girls 40.5 50.1  
Boys 59.5 49.9  
Age, mean year (n = 1337) 12.7 (n = 205) 12.6 (n = 1132) 0.003
Age groups (n = 205) (n = 1132) 0.030
11-12 years 65.4 72.8  
13-14 years 34.6 27.2  
BMI, mean kg/m2 (n = 1266) 19.3 (n = 180) 18.8 (n = 1086) 0.016
Weight status (BMI thresholds)*** (n = 1266): (n = 180) (n = 1086) 0.200
Under-/normal weight 82.7 86.3  
Overweight/obese 17.3 13.7  
Self-reported PA in leisure time, % (n = 1313): (n = 194) (n = 1119) 0.042
- Performs sports several times a week (vigorous activity) 47.4 45.1  
- Doing sport approx. once a week, and besides that physical active every day, cycling, walking, playing (moderate activity) 19.6 28.4  
- Enjoy being physical active, but do not attend any sport clubs. Cycle, walk and are physical active when playing (light activity) 24.7 21.0  
- Prefer to watch TV, play video games, listening to music or other sedentary behaviour (sedentary) 8.3 5.5  
Self-reported sedentary leisure time, %: 4 h + of daily sedentary time (TV, computer, reading) in weekdays and weekend days (n = 1313) 66.0 (n = 194) 62.3 (n = 1119) 0.326
  1. N varies due to different data sources.
  2. Number of valid days and daily wear time were fixed to 5 days of 10 hours in defining valid data.
  3. *No valid data in any of the non-wear settings. **Valid data when using the 10, 20, 30 or 60/90 minutes of non-wear criterion. ***Age and sex standardized [27].