Maximum partial likelihood parameter estimates from the model , utilizing each of the three distance metrics considered (geographic distance, work commutes and air traffic).

Spatial models were not fit to the 2008/2009 epidemic because of lack of detectable influenza epidemic onset times (estimated from outpatient influenza-like-illness time series) in a sufficient number of locations.空间模型（spatial models）无法适配2008/2009年的流感疫情，原因在于：在足够数量的监测地点中，难以获取由门诊流感样病例（influenza-like-illness）时间序列估算得到的可检测流感疫情暴发起始时间。