Fig. 1
From: Longitudinal data collection to follow social network and language development dynamics at preschool
Signal strength statistics during interactions and no-interactions. (a) Standard deviation (x-axis) and average (y-axis) of RSSI values recorded by RX devices and coming from badges either worn (green dots) or not worn (red dots) by a child participant. Annotation is based on ground truth collected at the school (i.e. known absences). Within this uncleaned set of data, cases of misclassification are likely due to wrong manipulations. Red points in the green zone would be badges of absent children approached or manipulated by other classmates, but such cases will be solved during the Initial Data Cleaning procedure based on recorded absences. However, green points in the red zone would be badges unused or dropped by present children (notably at the beginning and end of a half-day of data collection), and these are such cases that will be filtered by the described cleaning procedure in Subsection Issue 2. Settings: window size = 3 minutes, step = 1 minute. Plot based on observational data from 7 classes, i.e. 163 children and 7 RX badges, during 1 week of data collection. (b) Distributions of RSSI values shown as box-plots for pairs of children observed at different experimentally-fixed distances and relative orientations (from GT2 dataset), and used to parameterize the cleaning procedure described in Subsection Issue 3. Black diamonds indicate the average value and bar is the median value. Position-distance (x-axis): letters indicate relative orientation as ‘FF’ face to face, ‘SS’ side by side, ‘BB’ back to back; and the following number indicates the distance in centimeters. Plot based on observational data from: FF-10: 1 pair, 120 seconds, 48 data points; FF-100: 5 pairs, 2765 seconds, 1106 data points; FF-200: 2 pairs, 720 seconds, 288 data points; SS-100: 1 pair, 240 seconds, 96 data points; BB-100: 1 pair, 335 seconds, 134 data points. (c) Correlation between distance (x-axis) and RSSI values (y-axis) shown as a density plot (from GT3 dataset). Plot based on observational data from 1 class with 28 participants, 8 observation sessions for a total of 302 minutes, 62965 data points.
