title: MEM spectral analysis for predicting influenza epidemics in Japan.
abstract: OBJECTIVE
  The prediction of influenza epidemics has long been the focus of attention in epidemiology and mathematical biology. In this study, we tested whether time series analysis was useful for predicting the incidence of influenza in Japan.
  
  
  METHODS
  The method of time series analysis we used consists of spectral analysis based on the maximum entropy method (MEM) in the frequency domain and the nonlinear least squares method in the time domain. Using this time series analysis, we analyzed the incidence data of influenza in Japan from January 1948 to December 1998; these data are unique in that they covered the periods of pandemics in Japan in 1957, 1968, and 1977.
  
  
  RESULTS
  On the basis of the MEM spectral analysis, we identified the periodic modes explaining the underlying variations of the incidence data. The optimum least squares fitting (LSF) curve calculated with the periodic modes reproduced the underlying variation of the incidence data. An extension of the LSF curve could be used to predict the incidence of influenza quantitatively.
  
  
  CONCLUSIONS
  Our study suggested that MEM spectral analysis would allow us to model temporal variations of influenza epidemics with multiple periodic modes much more effectively than by using the method of conventional time series analysis, which has been used previously to investigate the behavior of temporal variations in influenza data.
authors.affiliation: Department of Hygiene, Sapporo Medical University School of Medicine, S-1, W-17, Chuo-ku, Sapporo 060-8556, Japan. sumi@sapmed.ac.jp
authors.forename: Ayako
authors.initials: A
authors.lastname: Sumi
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Kamo
mesh_terms: D058872:Epidemics; D006801:Humans; D015994:Incidence; D007251:Influenza, Human / Q000453:epidemiology*; D007564:Japan / Q000453:epidemiology; D016018:Least-Squares Analysis; D017711:Nonlinear Dynamics; D010507:Periodicity; D011159:Population Surveillance / Q000379:methods*; D013997:Time Factors