*4.5. Space-Time Cluster Analysis*

A space-time permutation technique was applied to examine the presence of space-time clusters in Gifu Prefecture. The upper limit on the geographical size of the cluster was set as 23 km, the minimum time aggregation as seven days, and the maximum temporal cluster size as 50% of the total study period (default setting) [32]. A Monte Carlo process was implemented using 999 replications to test for the presence of candidate clusters (*P* < 0.05). Analyses were conducted in SaTScan software v9.6 (Kulldorff, Boston, MA, USA) [46].
