The use of epidemiological tools in conflict-affected populations: open-access educational resources for policy-makers

Table of Contents

1. Welcome
2. Introduction: Epidemiology in crises
3. Ethical issues in data collection
4. Need for epidemiologic competence
5. Surveys - Introduction
6. Surveys - Description of sampling methods
7. Surveys - Sampling error, bias, accuracy, precision, & sample size
8. Surveys - Resources required for surveys
9. Surveys - Critiquing survey reports
   1. Introduction
   2. Objectives
   3. Justification for survey
   4. General procedures
   5. Outcomes and risk factors
   6. Sample size
   7. Sampling method
   8. Data analysis
   9. Data analysis
   10. Discussion
   11. Conclusions
   12. Recommendations
10. Surveillance - When to do surveillance
11. Surveillance - Methods
12. Surveillance - Common problems
13. Programme data
14. Rapid assessment
15. Mortality - Indicators and their measurement
16. Mortality - Data sources
17. Mortality - Interpretation and action
18. Nutrition - Introduction and background
19. Nutrition - Indicators and their measurement
20. Nutrition - Data sources
21. Nutrition - Interpretation and action
22. Health services
23. Vaccination programmes
24. Water supply, sanitation, and shelter
25. Violence
26. Presentation of results
27. Formulating conclusions and recommendations
28. Dissemination and action

Sampling method

(go to Outline)

Have the survey managers clearly defined the sampling universe? That is, have they described the population from which the sample was chosen? This must be clearly defined in order to know: a) who is eligible for inclusion in the survey sample, and b) to what population the results of the survey can be generalized.

Was the sampling frame out of date and if so, was it adjusted in any way? The sampling frame is the list of units from which the sampling was done. In cluster surveys, there may be a sampling frame consisting of a list of villages from which 30 are selected as clusters. If the list is old, some villages may be missing or other villages may have incorrect populations. This could introduce sampling bias.

Is the sampling method described in enough detail? Could you, as the reader, spot mistakes and potential sources of sampling bias? The description of the sampling, and all other aspects of the survey methods, should be detailed enough so someone else could repeat the survey relying only on the survey report.

Just stating in a survey report "We selected a random sample of households in the refugee camp" is insufficient. Exactly how was this done? Walk through the camp and stop at any house they liked? (This is an unacceptable non-random convenience sample.) List all the households, assign each a number, and select them using a random number table? (This is excellent simple random sampling) (see section on Sampling methods)