MODELING SPATIAL SPREAD OF EPIDEMICS--MUMPS

              Lynne Billard, University of Georgia

                           ABSTRACT

       The Space Time Bilinear (STBL) model is a special form of a
  multiple bilinear time series  for use in modelling time series
  which exhibit bilinear behavior on a spatial neighborhood structure.
  The model is particularly appropriate for series that exhibit sudden
  shocks to the system such as would occur with a large disease outbreak.
  We present the model, and discuss estimation and prediction issues briefly.
  We then apply the model to some surveillance data for mumps in twelve north-
  eastern states in the U.S. over the years 1971-88 where there was a large
  outbreak in 1986-87, and predict cases for 1989 ( when another outbreak
  occurred). Results for the STBL model are compared with those obtained by
  fitting other time series models; we see that the STBL model performs
  most favorably.