Eur. Phys. J. B (2013) 86: 371
https://doi.org/10.1140/epjb/e2013-40209-x

Regular Article

Fluctuation in e-mail sizes weakens power-law correlations in e-mail flow

Computer and Network Center, Saga University, 840-8502 Saga, Japan

^a e-mail: matubara@cc.saga-u.ac.jp

Received: 14 March 2013
Received in final form: 5 July 2013
Published online: 4 September 2013

Abstract

Power-law correlations have been observed in packet flow over the Internet. The possible origin of these correlations includes demand for Internet services. We observe the demand for e-mail services in an organization, and analyze correlations in the flow and the sequence of send requests using a Detrended Fluctuation Analysis (DFA). The correlation in the flow is found to be weaker than that in the send requests. Four types of artificial flow are constructed to investigate the effects of fluctuations in e-mail sizes. As a result, we find that the correlation in the flow originates from that in the sequence of send requests. The strength of the power-law correlation decreases as a function of the ratio of the standard deviation of e-mail sizes to their average.