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
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
    1. Introduction
    2. Surveillance - Prospective death reporting
    3. Surveys (retrospective data collection)
    4. Recall period
    5. Determining the length of the recall period
    6. Data collection and the questionnaire
    7. Surveys - Quiz
    8. Surveys measuring mortality - Summary
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

Data collection and the questionnaire

(go to Outline)

When the recall period has been defined and the sample of households selected, survey teams interview respondents in each selected household regarding what has happened to their fellow household members during the recall period.

This is schematic diagram showing what may have happened to various household members during the recall period.

Some members of the household, such as member #1, lived in the household before the start of the recall period and are still in the household. Others, such as members #2 and #3, entered the household during the recall period, either by moving in or by being born into the household. Some members, such as members #4 and #5, were in the household at the beginning of the recall period, but left during the recall period, either by death or by moving out. And a few household members, such as member #6, entered and left the household during the recall period.

This figure shows an interview data collection form to determine the number and status of household members.

The interviewer firsts identifies a household member to answer questions. This can be any adult who lives in the household and is familiar with its members. The interviewer first asks "Who lived in the household at [name of festival or memorable occurrence]?" The interviewer must be sure that the beginning of the recall period is clearly understood by the respondent. The age and sex of each reported household member is recorded in columns #2 and #3. Column #4 is marked "Yes" for each of these people. The interviewer can also record names if this makes it easier to ask subsequent questions about each household member.

When this past household census is completed, the interviewer then asks if each of these people still lives in the household. This is recorded in column #5. Then the interviewer asks the status of people who lived in the household at the beginning of the recall period, but no longer live in the household. This is marked in column #6. Finally, the interviewer asks if there is anyone living in the household now who was not there at the beginning of the recall period. These people are then added to the household list by recording their ages and sexes in columns #2 and #3 and adding a "Yes" to column #5 and recording their status as alive in column #6.

The reason we ask the interview respondent to list all household members is to avoid asking directly about deaths and to avoid asking the respondent for the number of deaths. With the series of questions "Who lives in this household?" and "Where are these people now?" we avoid telling the respondent directly that we are interested in the number of deaths in the household. This way, if the respondent might wish to report more or fewer deaths for some reason, they would be less likely to do so because they may not understand that we are measuring mortality rates.

Once the household census table has been completed for all households selected for the survey sample, calculation of the crude mortality rate is merely summing the number of people in all the households in the survey sample. The average of the total household population at the beginning of the recall period and the total household population at the end of the recall period is the population denominator of the crude mortality rate. The number of deaths is the number of household members with "2" recorded for current status (column #6). The time period is the length of the recall period.

To calculate the age-specific mortality rate for children less than 5 years, sum only the number of children less than 5 years in each household both at the beginning and end of the recall period. The numerator is only deaths which occurred in children less than 5 years of age.