Table 2. Observed Mantel statistics.

All counties (N = 67)
Matrix	Correlation	P-value*	Lower CI	Upper CI
Euclidian distance	−0.03	0.5528	−0.079	0.006
Workflow (Intra-state)	0.14	0.0001	0.129	0.157
Workflow (Inter-state)	0.08	0.0260	0.058	0.099
Population	0.33	0.0004	0.310	0.389
Gravity (United States)†	0.11	0.0013	0.094	0.140
Gravity (Pennsylvania – Workflows)	0.19	0.0001	0.169	0.245
Gravity (Pennsylvania - Disease)	0.63	0.0001	0.593	0.656
Gravity(Pennsylvania - Disease) adjusting for:
Euclidian distance	0.63	0.001
Workflow (Intra-state)	0.62	0.001
Population	0.60	0.001

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.

^†Gravity matrix generated using parameters derived from Viboud et al.

^*Significance is determined at P<0.05.