Fig 1.
Top: Representative example of an area graph derived from wrist activity patterns of a child performing six investigator-observed behaviours (dashed boxes) shown for a MotionWatch 8 device attached to the non-dominant wrist.
The activity intensity was transformed into count values recorded every 30 seconds (epochs). Each type of behaviour was observed by stop-watch to last between 8 to 10 minutes. Bottom: Explanatory table describing the six behavioural activities at the top.
Fig 2.
Schematic description of ROC analysis procedures: A) One versus one (OvsO) and B) one versus the rest (OvsR) in order of descending intensities.
Double-sided arrows indicate the cut between categories for each ROC analysis. In OvsR, two sedentary categories (Sedentary craft + Recumbent listening) were merged into SED (for which ROC analysis were done only in OvsO, see S2 Table). Moreover, SED and MOA were collapsed into an composite ‘stationary PA’ class and tested against the composite ‘mobile PA’.
Table 1.
Descriptive characteristics of the participants (n = 30). Shown are means ± SD.
Table 2.
Mean ± SD of activity counts (counts/30 seconds) for each activity ranked from highest to lowest intensity measured at wrist-level and hip-level with ActiGraph GT3X and MotionWatch 8. Mean ± SD of the duration spent in activity is consistently similar.
Fig 3.
Relationship between activity counts/30s in 3-year-old children (n
= 30) during six activities ranging from ‘Motionless alert’ to ‘Vigorous PA’ for MotionWatch 8 (MW8) and ActiGraph (GT3X) at A) wrist position and B) hip position.The six activities are colour-coded in the graphs.
Fig 4.
Boxplots for six different intensity levels measured in 3-year old children with A) wrist-worn MotionWatch 8; B) hip-worn MotionWatch 8; C) wrist-worn ActiGraph GT3X; and D) hip-worn ActiGraph GT3X.
A value of ‘1’ was added to every count in order to increase the visibility of the lower end of the scale, in particular for the stationary, calmer activities through a logarithmic scale. Zero movement over 30s epoch is not uncommon, for example during a break. Box contains 50% of values (Interquartile range [IQR] with values between Q1 and Q3 (25th–75th percentile), mid-line represents median, Whiskers represent min-max ([Q1 − 1.5 * IQR] − Q3 + 1.5 * IQR]).
Table 3.
ROC-AUC analysis for wrist-worn MotionWatch 8 and ActiGraph GT3X devices after collapsing categories. See details for collapsed categories in Fig 2.
Table 4.
ROC-AUC analysis for hip-worn MotionWatch 8 and ActiGraph GT3X devices after collapsing categories. See details for collapsed categories in Fig. 2.