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220905P - CROSS-SECTIONAL STUDY 2: ECOLOGIC DESIGN

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Presented at a Clinical Research Course for Pediatric Residency Program held at King Fahad Medical City, Riyadh on Thursday, 27 January 2022 (13:00 – 15:00 HRS). By Professor Omar Hasan Kasule Sr. MB ChB (MUK). MPH (Harvard), DrPH (Harvard) Professor of Epidemiology and Bioethics


KEYWORDS

  • Survey report
  • The survey, Field Survey
  • The survey, Health Surveys
  • The survey, Morbidity Survey
  • The survey, Nutrition Survey


ECOLOGIC DESIGN

  • Ecological studies, exploratory or analytic, study aggregate and not individual information.
  • Groups commonly used are schools, factories, and countries.
  • Exposure is measured as an overall group index.
  • Outcome is measured as rates, proportions, and means.
  • The correlation and regression coefficients are used as effect measures.


ADVANTAGES OF ECOLOGIC / CORRELATION STUDIES

  • Low cost,
  • Convenience,
  • Easy analysis,
  • Easy interpretation.


DISADVANTAGES OF ECOLOGIC STUDIES

  • They generate but cannot test hypotheses.
  • They cannot be used in definitive etiological research.
  • They suffer from ecological fallacy (relation at the aggregate is not true at the individual level). They lack data to control for confounding.
  • Data is often inaccurate or incomplete.
  • Collinearity is a common problem.