Fig. 5.

Probability density function of time lags between co-location degree centrality and weekly basic reproduction numbers (blue bar plot). a With the average number of confirmed cases on March 31, 2020, for the counties in each time-lag group (line plot with error bar); and b with the population size of a county. Positive time lag indicates degree centrality decreases prior to the decrease of basic reproduction number (indicating proactive social distancing), while negative time lag indicates the basic reproduction number decreases prior to the decrease of degree centrality (indicates obeying stay-at-home orders). The error bar represents the two-side 95% confidence interval. Some extreme numbers of confirmed are considered as outliers and are not included in the analysis