Figure 2From: Visualization and exploratory analysis of epidemiologic data using a novel space time information systemParticipant movement over 20 years Cases (circles) and controls (squares) continue to move in, out, and around the study area. In 1960 there were two cases and one control. By 1982 four more cases and two more controls moved into the study area and in 2001 the same number of cases and controls remain in the area however one case and one control have moved addresses.Back to article page