Effect of spatial resolution on power to detect significant space-time clusters.

<p>Effect of spatial resolution on power to detect significant space-time clusters at significance level α = 0.05 for varying sizes of cluster radii of 0–16 km (A), 17–32 km (B) and 33–48 km (C). Each line represents disease case data aggregated to different spatial resolutions – the address level (solid line with solid squares), the ZIP code level (dashed line with open squares) and county level (dotted line with triangles). Relative risk (abscissa x-axis) describes the intensity of the artificially created clusters, where RR = 1 indicates the risk of a disease case occurring inside the cluster area is equivalent to that of occurring outside the cluster area (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0048036#pone-0048036-g001" target="_blank">Fig. 1</a>). RR = 10 indicates risk is 10 times higher inside the cluster area relative to outside the area.