title: Mapping disease at an approximated individual level using aggregate data: a case study of mapping New Hampshire birth defects.
abstract: BACKGROUND
  Limited by data availability, most disease maps in the literature are for relatively large and subjectively-defined areal units, which are subject to problems associated with polygon maps. High resolution maps based on objective spatial units are needed to more precisely detect associations between disease and environmental factors.
  
  
  METHODS
  We propose to use a Restricted and Controlled Monte Carlo (RCMC) process to disaggregate polygon-level location data to achieve mapping aggregate data at an approximated individual level. RCMC assigns a random point location to a polygon-level location, in which the randomization is restricted by the polygon and controlled by the background (e.g., population at risk). RCMC allows analytical processes designed for individual data to be applied, and generates high-resolution raster maps.
  
  
  RESULTS
  We applied RCMC to the town-level birth defect data for New Hampshire and generated raster maps at the resolution of 100 m. Besides the map of significance of birth defect risk represented by p-value, the output also includes a map of spatial uncertainty and a map of hot spots.
  
  
  CONCLUSIONS
  RCMC is an effective method to disaggregate aggregate data. An RCMC-based disease mapping maximizes the use of available spatial information, and explicitly estimates the spatial uncertainty resulting from aggregation.
authors.affiliation: Department of Geography, Dartmouth College, 6017 Fairchild, Hanover, NH 03755, USA. xun.shi@dartmouth.edu
authors.forename: Xun
authors.initials: X
authors.lastname: Shi
authors.forename: Stephanie
authors.initials: S
authors.lastname: Miller
authors.forename: Kevin
authors.initials: K
authors.lastname: Mwenda
authors.forename: Akikazu
authors.initials: A
authors.lastname: Onda
authors.forename: Judy
authors.initials: J
authors.lastname: Reese
authors.forename: Tracy
authors.initials: T
authors.lastname: Onega
authors.forename: Jiang
authors.initials: J
authors.lastname: Gui
authors.forename: Margret
authors.initials: M
authors.lastname: Karagas
authors.forename: Eugene
authors.initials: E
authors.lastname: Demidenko
authors.forename: John
authors.initials: J
authors.lastname: Moeschler
mesh_terms: D000293:Adolescent; D000328:Adult; D000013:Congenital Abnormalities / Q000453:epidemiology*; D005260:Female; D006801:Humans; D008875:Middle Aged; D009010:Monte Carlo Method; D009513:New Hampshire / Q000453:epidemiology; D019371:Topography, Medical; D055815:Young Adult
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