Table 4. Space-time clusters with higher incidence in Shandong Province, China from 2005–2014.

Cluster type	Time frame	Cluster areas(n)	Observed cases	Expected cases	Radius	Relative risk	p value
Most likely	2012–2013	5	6333	699.82	34.68	9.48	<0.0001
Secondary	2008–2011	2	6350	1104.47	4.88	6.00	<0.0001
2nd Secondary	2012–2013	21	10736	3639.79	76.00	3.13	<0.0001
3rd Secondary	2005–2005	1	1442	81.63	0.00	17.86	<0.0001
4th Secondary	2011–2014	5	5053	1475.12	23.28	3.53	<0.0001
5th Secondary	2009–2013	8	6876	3206.19	58.92	2.21	<0.0001
6th Secondary	2012–2013	13	4298	2503.22	77.76	1.74	<0.0001
7th Secondary	2013–2014	3	1261	623.13	37.03	2.03	<0.0001
8th Secondary	2008–2008	3	736	297.34	40.86	2.48	<0.0001
9th Secondary	2012–2013	12	4189	2979.08	119.16	1.42	<0.0001