Baseline Mapping — Establish the Baseline Population and Maps of Geographic Clusters
Step 9
Before birth and death surveillance begins in each cluster, it is important to create maps and enumerate the population of each study cluster.
Mapping Clusters
A team of cartographers should visit all clusters to create a digital map of each cluster and obtain their geocoordinates. When census enumeration areas (EA) are used as the sampling frame, sketch maps of each EA are often available from the national statistics office (NSO). These may be used to support the refinement of the clusters’ boundaries. It is essential to work with cartography experts from the NSO, who should lead the training for the mapping teams. In general, two individuals will be sufficient to map each cluster within 2-3 days.
For each EA, the boundaries are delimited by tracking all the boundaries, often using a motorcycle and taking the GPS coordinates for each corner and also other locations on the boundaries, using a tablet computer. Then all households located within the EA are visited to assign a unique household identification number and collect basic information, including the name of the head of the household, the total number of people living in the household (household size), and the geocoordinates. If there are multiple EAs that form a cluster, all EAs within the same cluster are mapped using the same procedure.
Two main challenges frequently arise during the cartography. The first concerns largely populated clusters (e.g. more than 300 households), which may exceed a reasonable number of households for effective work. In this case, the cluster may be split, and one segment may be randomly selected prior to the fieldwork. This process of splitting large clusters must be discussed with NSO cartographers. Also, the realities and practicalities of the field work must be considered, including population distribution and accessibility.
The second challenge concerns clusters that span communities without clearly defined physical boundaries. In these situations, boundaries may be adjusted to ensure that clusters are geographically coherent and to minimize the risk of surveillance outside the designated area. These decisions should be clearly defined and incorporated into the training of mapping team.
Following the mapping fieldwork, clusters and EAs maps are produced, including plotted locations of households. These maps will later be printed and distributed to community workers and data collection teams.
Baseline Household and Population
Following cartography, community workers, their supervisors, and the VASA interviewers use the maps and household lists to revisit every household in the cluster to collect detailed information on each household member and the household using tablets or mobile phone loaded the household listing questionnaire. A household is defined as a person or group of related or unrelated persons who live together in the same dwelling unit(s), who acknowledge one adult male or female as the head of the household, who share the same housekeeping arrangements, and who are considered a single unit. Each country has its own definition of a household, which may vary slightly from this definition, but generally, the definition is very similar.
The data collectors request the permission of the head of the household to participate in the study by using the household consent form document. They should clearly inform the head of the household that subsequent visits will follow in case of any event or the monthly/bimonthly household visit. Then they conduct the baseline interview, which involves interviewing the head of the household or any adult member that can provide information on each member of the household (full names including surnames, age, sex, education, and marital status, etc.). They may also collect information about the household’s durable assets. It is recommended that the mapping and household listing be updated every 2-3 years.
The household listing serves as an opportunity to introduce the community worker to each household and get buy-in and support from the community. It is therefore essential that the community worker is fully involved in the activity. A list of households with their ID will later be printed and provided to the community worker to support the ongoing community surveillance.
During the initial household visit, data collectors also record any pregnancies, births and deaths that have occurred in the past three months. Active community surveillance of vital events should start once the household listing is completed.
Baseline Supervision and Quality Assurance
During the household listing phase, supervisors conduct data quality control by revisiting a sample of households, repeating the interview process, and comparing the data to that collected by the data collectors. Feedback is then provided to data collectors, who may require retraining to ensure adherence to data collection procedures and maintain data quality.
Scaling Up Data Collection
During the planning phase, the project leaders should carefully discuss the best strategies to scale up the system, taking into consideration geographic and cultural contexts as well as country health priorities. A phased or stepwise implementation roll-out is highly recommended, meaning that the system is first implemented in a subgroup of geographic areas, rather than nationwide. This approach is essential to increase the likelihood of successful implementation and to allow faster learning for roll-out.
| Last updated |
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| Apr 30, 2026 |