Public health is of major concern for society, public and private organizations, communities, and individuals. Often the question is raised whether there are disparities of illness and health problems across areas (see, e.g., Chapters 2, 3, 14, and 15). An increasing amount of information on individuals is collected in this respect. Bayesian methods in disease mapping based on census or population registry data are well developed and are used in a fairly standard manner (see, e.g., Lawson et al. , Elliott et al. , and Waller and Gotway  for reviews of the methods, and Chapters 6, 7, and 20 in this book). Note that such population registries or census data record information pertaining to each member of the population of an area. Historically, focus was on the construction of cancer atlases and on mapping of other rare diseases based on registry data (see, e.g., Kemp et al.  and Devesa et al. ).