title: Prediction of activity type in preschool children using machine learning techniques.
abstract: OBJECTIVE
  Recent research has shown that machine learning techniques can accurately predict activity classes from accelerometer data in adolescents and adults. The purpose of this study is to develop and test machine learning models for predicting activity type in preschool-aged children.
  
  
  METHODS
  Participants completed 12 standardised activity trials (TV, reading, tablet game, quiet play, art, treasure hunt, cleaning up, active game, obstacle course, bicycle riding) over two laboratory visits.
  
  
  METHODS
  Eleven children aged 3-6 years (mean age=4.8±0.87; 55% girls) completed the activity trials while wearing an ActiGraph GT3X+ accelerometer on the right hip. Activities were categorised into five activity classes: sedentary activities, light activities, moderate to vigorous activities, walking, and running. A standard feed-forward Artificial Neural Network and a Deep Learning Ensemble Network were trained on features in the accelerometer data used in previous investigations (10th, 25th, 50th, 75th and 90th percentiles and the lag-one autocorrelation).
  
  
  RESULTS
  Overall recognition accuracy for the standard feed forward Artificial Neural Network was 69.7%. Recognition accuracy for sedentary activities, light activities and games, moderate-to-vigorous activities, walking, and running was 82%, 79%, 64%, 36% and 46%, respectively. In comparison, overall recognition accuracy for the Deep Learning Ensemble Network was 82.6%. For sedentary activities, light activities and games, moderate-to-vigorous activities, walking, and running recognition accuracy was 84%, 91%, 79%, 73% and 73%, respectively.
  
  
  CONCLUSIONS
  Ensemble machine learning approaches such as Deep Learning Ensemble Network can accurately predict activity type from accelerometer data in preschool children.
authors.affiliation: Faculty of Engineering and Information Science, University of Wollongong, Australia. Electronic address: markus@uow.edu.au.
authors.forename: Markus
authors.initials: M
authors.lastname: Hagenbuchner
authors.affiliation: Faculty of Social Sciences, Early Start Research Institute, University of Wollongong, Australia. Electronic address: dylanc@uow.edu.au.
authors.forename: Dylan P
authors.initials: DP
authors.lastname: Cliff
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, Australia. Electronic address: s.trost@qut.edu.au.
authors.forename: Stewart G
authors.initials: SG
authors.lastname: Trost
authors.affiliation: Faculty of Engineering and Information Science, University of Wollongong, Australia. Electronic address: vtn966@uow.edu.au.
authors.forename: Nguyen
authors.initials: N
authors.lastname: Van Tuc
authors.affiliation: School of Medicine, University of Wollongong, Australia. Electronic address: greg_peoples@uow.edu.au.
authors.forename: Gregory E
authors.initials: GE
authors.lastname: Peoples
mesh_terms: D061725:Accelerometry; D000203:Activities of Daily Living; D001642:Bicycling; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D000069550:Machine Learning; D008297:Male; D008962:Models, Theoretical; D009043:Motor Activity; D016571:Neural Networks, Computer; D010988:Play and Playthings; D012420:Running; D016138:Walking
keywords: Accelerometry; Exercise; Neural networks; Pattern recognition; Physical activity; Validity