title: A cross-sectional ecological study of spatial scale and geographic inequality in access to drinking-water and sanitation.
abstract: BACKGROUND
  Measuring inequality in access to safe drinking-water and sanitation is proposed as a component of international monitoring following the expiry of the Millennium Development Goals. This study aims to evaluate the utility of census data in measuring geographic inequality in access to drinking-water and sanitation.
  
  
  METHODS
  Spatially referenced census data were acquired for Colombia, South Africa, Egypt, and Uganda, whilst non-spatially referenced census data were acquired for Kenya. Four variants of the dissimilarity index were used to estimate geographic inequality in access to both services using large and small area units in each country through a cross-sectional, ecological study.
  
  
  RESULTS
  Inequality was greatest for piped water in South Africa in 2001 (based on 53 areas (N) with a median population (MP) of 657,015; D = 0.5599) and lowest for access to an improved water source in Uganda in 2008 (N = 56; MP = 419,399; D = 0.2801). For sanitation, inequality was greatest for those lacking any facility in Kenya in 2009 (N = 158; MP = 216,992; D = 0.6981), and lowest for access to an improved facility in Uganda in 2002 (N = 56; MP = 341,954; D = 0.3403). Although dissimilarity index values were greater for smaller areal units, when study countries were ranked in terms of inequality, these ranks remained unaffected by the choice of large or small areal units. International comparability was limited due to definitional and temporal differences between censuses.
  
  
  CONCLUSIONS
  This five-country study suggests that patterns of inequality for broad regional units do often reflect inequality in service access at a more local scale. This implies household surveys designed to estimate province-level service coverage can provide valuable insights into geographic inequality at lower levels. In comparison with household surveys, censuses facilitate inequality assessment at different spatial scales, but pose challenges in harmonising water and sanitation typologies across countries.
authors.affiliation: Geography and Environment, University of Southampton, University Road, Southampton, SO17 1BJ, UK. yurhcp@126.com.
authors.forename: Weiyu
authors.initials: W
authors.lastname: Yu
authors.affiliation: UNICEF, 3 UN Plaza, New York, USA. rbain@unicef.org.
authors.forename: Robert E S
authors.initials: RE
authors.lastname: Bain
authors.affiliation: Geography and GIS Department, Faculty of Arts, Alexandria University, Alexandria, Egypt. gisshawky@yahoo.com.
authors.forename: Shawky
authors.initials: S
authors.lastname: Mansour
authors.affiliation: Geography and Environment, University of Southampton, University Road, Southampton, SO17 1BJ, UK. j.a.wright@soton.ac.uk.
authors.forename: Jim A
authors.initials: JA
authors.lastname: Wright
mesh_terms: D003430:Cross-Sectional Studies; D003906:Developing Countries; D060766:Drinking Water / Q000592:standards*; D040362:Geographic Information Systems; D062305:Geographic Mapping; D006801:Humans; D012499:Sanitation / Q000592:standards*; D012959:Socioeconomic Factors; D014881:Water Supply / Q000592:standards*
chemical_list: D060766:Drinking Water