Burstiness of human physical activities and their characterisation

Human behaviour is heterogeneous and temporally fluctuates. Many studies have focused on inter-event time (IET) fluctuations and have reported that the IET distributions show a long-tailed distribution, which cannot be explained by a stationary Poisson point process. Such a phenomenon observed in IET distributions is known as burstiness. Burstiness has also been reported for human physical activity, but the mechanism underlying it has not been clarified. In this study, we prospectively collected human physical activity data while specifying the age of the subjects and their situations (for example, children’s play and adults’ housework), and we analysed their event time series data. We confirmed the burstiness in both children and adults. For the first time, burstiness was studied in physical activities of children between the ages of 2 and 5. This is important because it indicates that burstiness is not an acquired feature. We also confirmed that the IET distributions for each situation show a long tail. This result partially rejects the possibility that the burstiness of physical activities can be explained by multiple stationary Poisson process model. Our results are important for a deeper understanding of the human burst phenomenon and its mechanisms.