Parameter estimates for gravity models (disease spreads and workflows) and the corresponding 95% confidence intervals (CI).

<p>Parameter estimates for gravity models (disease spreads and workflows) and the corresponding 95% confidence intervals (CI).</p

Characteristics of reported influenza cases in Pennsylvania, USA, 2003–2008 influenza seasons.

*<p>Nineteen subjects have missing date of birth.</p

Descriptive statistics and results of logistic regression model (Dependent variable are counties designated HIGH-HIGH in Moran's LISA cluster analysis, counties = 8).

*<p>Significance: P-value<0.05.</p

Association of workflows, population and distance.

<p>(y-axis and z-axis log10 scale). The relationship between workflows (z-axis), population size (y-axis) and distance (x-axis).</p

Observed Mantel statistics.

<p>Pearson correlation of the dissimilarity matrices and Spearman rank correlations of the epidemic time series for all counties (N = 67). P-values and the corresponding 95% confidence intervals (CI) are presented. Gravity Pennsylvania refers to the gravity model fitted to Pennsylvania-specific data.</p>†<p>Gravity matrix generated using parameters derived from Viboud et al.</p>*<p>Significance is determined at P<0.05.</p

Weekly case incidence for 67 counties by population size.

<p>Intensity image displace weekly case incidence (per 10,000 persons) sorted by population size. The counties are arranged from largest population size (67 = Philadelphia) to the smallest population size (1 = Forest). The surveillance system defines each influenza season to begin in the 40^th week of the calendar year through the last week of April of the following year.</p

County characteristics.

*<p>186 weeks over 6 epidemic seasons (31*6).</p

Map of Pennsylvania, US detailing the county boundaries, urban areas, and transportation networks.

<p>Pittsburgh in Allegheny County is highlighted in the West and Philadelphia is highlighted in the South East. Both urban areas have international airports and are connected by a major interstate highway.</p

Epidemic width estimates and confidence intervals.

*<p>Sigma measures the epidemic length.</p

Correlation of weekly time series with distance and population size.

<p>A) Synchrony as a function of distance. The spline function (middle curve) is presented with a 95% confidence interval (outer curves). B) Synchrony as a function of population size (product of population i, j). The distribution of population was categorized by quartile. The boxplot within each quartile represent the distribution of the correlation of population between pairs of counties.</p