Zipf's law in activity schedules

This distribution, commonly referred to as Zipf’s law, obeys a power-law which has been observed in many natural and social processes. It was actually first observed by Felix Auerbach in 1913 (Auerbach, cited in Zipf 1949, Newman 2005). He discovered that city size is governed by such a power-law. Willis (Willis, cited in Chen 1980) noted in 1922 that the size distribution of biological genera follows a power-law distribution. Zipf, an American linguist, described a power-law distribution in word frequency in 1949 (although it had first been noticed by Estroup in 1916 (Estroup, cited in Ki Baek et al. 2011)). Zipf famously investigated this distribution more in detail, revealing that the same power-law distribution holds for a large number of events in different domains, ranging from sizes of earthquakes, annual income of companies, solar flares, to the number of citations received on papers (Fujiwara, 2004; Furusawa and Kaneko, 2003; Maillart et al., 2008; Newman, 2005; Okuyama et al., 1999).