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Presented at Research Methodology Course at NAAFH Hafr al Batin 28 December 2020 by Professor Omar Hasan Kasule Sr. MB ChB (MUK), MPH (Harvard), DrPH (Harvard), Member of the Institutional Review Board, King Fahad Medical City
KEY WORDS
• Survey report
• Survey, Field Survey
• Survey, Health Surveys
• Survey, Morbidity Survey
• 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.