Apparent disease clusters may be pure artifacts of where you draw the boundary.

Evidence

Some epidemiologists at the CDC, for example, explained apparent leukemia clusters by analogy to the “Texas sharpshooter” effect: a man shoots at the side of a barn and then proceeds to draw targets around the holes. He makes every shot into a bull’s-eye. If an epidemiologist were to draw a circle around, say, the greater Boston area, he would find an incidence of leukemia comparable with the rest of the United States. Draw a circle around Woburn and he’d find a worrisome elevation. Draw a circle around the Pine Street neighborhood and he’d find an alarming cluster. Was it a real cluster? Or was he just drawing bull’s-eyes where he found bullet holes? — , Harr Jonathan - A Civil Action, 160

Categorization

• DEEPTHINKING: The Texas sharpshooter analogy quietly undermines the entire premise of local environmental causation — a reader could sit with whether any cluster is ever ‘real’ or only an artifact of framing.
• XREF: Connects to the archive/quantification material on how crime statistics are constructed through discursive practices, not neutral counting — same problem of manufactured units.
• SEED: Article angle: ‘The Sharpshooter’s Circle’ — how choosing a boundary pre-determines whether a cluster looks real, from leukemia to cancer to crime maps.