Lesson 5: Descriptive Studies (2) Health Surveys

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Health Surveys

Recently, a group of medical students and health professionals from the Penn State College of Medicine agreed to work with a community leader in San Pablo, Ecuador to improve population health. The first step in the collaboration was an assessment of the current health of the population. Since public sanitation was minimal in this rural area, there was particular concern about intestinal diseases. The objective of the assessment was "to establish a population-based estimate of the prevalence of selected health conditions, including diarrhea and respiratory illness, and assess water sources and sanitation for households in San Pablo."

How would this be accomplished? There was little information available from public health (surveillance) records for this area. The team decided to conduct door-to-door, in-person interviews in the local language (Spanish). Their target respondent was an adult who was knowledgeable about the health of all the residents in the house and about selected household characteristics. What questions should be asked? How many households should be surveyed? How would households be selected for the survey?

We'll learn more about this particular experience and how such questions may be addressed as we study this week's lesson. When you have completed this lesson, you will be able to do the following:

  1. Identify advantages and disadvantages of surveys
  2. Differentiate between sampling strategies in order to select an appropriate sampling scheme for a survey
  3. State factors contributing to reliability and validity of a survey instrument.
  4. Calculate the following summary statistics from a 2 x 2 epidemiological table: Ratio of Prevalence to Exposure;  Ratio of Prevalence of Disease; Differences of Prevalence in Exposure and Disease Prevalence; Exposure Odds-Ratio
  5. Compare and contrast  5 health surveys conducted in the US with regard to target population, sampling strategy and purpose.