title: DSS and DHS: longitudinal and cross-sectional viewpoints on child and adolescent mortality in Ethiopia.
abstract: BACKGROUND
  In countries where routine vital registration data are scarce, Demographic Surveillance Sites (DSS: locally defined populations under longitudinal surveillance for vital events and other characteristics) and Demographic and Health Surveys (DHS: periodic national cluster samples responding to cross-sectional surveys) have become standard approaches for gathering at least some data. This paper aims to compare DSS and DHS approaches, seeing how they complement each other in the specific instance of child and adolescent mortality in Ethiopia.
  
  
  METHODS
  Data from the Butajira DSS 1987-2004 and the Ethiopia DHS rounds for 2000 and 2005 formed the basis of comparative analyses of mortality rates among those aged under 20 years, using Poisson regression models for adjusted rate ratios.
  
  
  RESULTS
  Patterns of mortality over time were broadly comparable using DSS and DHS approaches. DSS data were more susceptible to local epidemic variations, while DHS data tended to smooth out local variation, and be more subject to recall bias.
  
  
  CONCLUSIONS
  Both DSS and DHS approaches to mortality surveillance gave similar overall results, but both showed method-dependent advantages and disadvantages. In many settings, this kind of joint-source data analysis could offer significant added value to results.
authors.affiliation: Umeå International School of Public Health, Umeå University, Umeå, Sweden. peter.byass@epiph.umu.se.
authors.forename: Peter
authors.initials: P
authors.lastname: Byass
authors.forename: Alemayehu
authors.initials: A
authors.lastname: Worku
authors.forename: Anders
authors.initials: A
authors.lastname: Emmelin
authors.forename: Yemane
authors.initials: Y
authors.lastname: Berhane