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
   1. Bias and sampling error
   2. Bias and sampling error 2
   3. Bias
   4. Measurement bias
   5. Sampling bias
   6. Sampling error
   7. Bias and sampling error - Quiz
   8. Confidence intervals
   9. Confidence intervals - Quiz
   10. Accuracy and precision - theory
   11. Sample size
8. Surveys - Resources required for surveys
9. Surveys - Critiquing survey reports
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

Bias and sampling error 2

(go to Outline)

This schematic shows the two reasons why a survey result may be different from the true level in the population.

Some of the difference between the survey estimate and the true level in the population is made of bias and some is made of sampling error.