Factors in micronutrient survey design and protocol development
The survey protocol, budget and timeline should be drafted after the overall objectives of the survey have been agreed and defined. The protocol needs to include decisions on the following aspects of the survey, details of which are presented in subsequent modules of this manual.
Precision of estimates for the main survey indicators within each stratum
The required precision of estimates at the stratum and national levels is determined somewhat by the expected programmatic use. For example, a relatively precise estimate may be required to determine whether an intervention implemented for the past two years has had an impact, that is, whether a change from the baseline estimate is real. Module 4: Survey design describes factors to consider in these decisions in more detail.
Sample size calculation and sampling design
Agreement must be reached on the calculated sample size, the level of stratification and the balance between the number of clusters and the number of samples targeted for collection from each cluster. For these decisions, the overall budget and time available need to be taken into consideration. Module 5: Sample size presents detailed guidance on calculating sample size and designing the survey sample for different contexts.
Method of collecting data
An important decision to make during the design phase is how data will be collected and managed. In the past, most surveys used paper-based questionnaires with manual data entry. Currently, digital data collection using methods such as computer-assisted personal interviews (CAPIs) or Open Data Kit (ODK) are increasingly the default option, using either small computer tablets or large-screen smart phones. The advantages and disadvantages to each method are described further in Module 4: Survey design.
Selecting biomarkers, food sample nutrients, and clinical indicators
Because there may be multiple biomarkers for a particular micronutrient, decisions need to be made about which are the most appropriate ones for the survey context. Information to guide these decisions can be found in Module 2: Indicators of programme coverage, specimen selection, management, and analysis and Module 3: Biomarker selection and specimen handling.”.
Decisions on the biomarkers and food sample nutrients to analyse will affect such factors as the needed skills and expertise of fieldworkers, the estimated time required per survey participant and survey household, fieldwork supplies and logistics, laboratory supplies, and the overall budget.
Clinical signs and symptoms of micronutrient deficiency or excess are no longer commonly included in large, complex population-based surveys because:
they typically appear only when a deficiency has reached a severe level, whereas blood and urine biomarkers can assess deficiency and risk of excess at a subclinical, less severe, stage;
once a micronutrient intervention has been implemented for a period of time, any prior clinical signs among the population may occur infrequently or be an indication of previous deficiency, in which case they are not a reliable indicator of current status. For example, a large nodular goitre from previous iodine deficiency may remain for many years even when a person’s diet becomes sufficient in iodine;
reliable assessment of clinical micronutrient-related disease signs and symptoms may require specialized equipment and personnel, for example an ophthalmologist to accurately assess xerophthalmia, which occurs with severe vitamin A deficiency; or
many signs and symptoms of non-optimal micronutrient status, such as anorexia, diarrhoea, fatigue, and weakness, have other possible causes that would be difficult to differentiate.
Supplies, equipment, and logistics
The supplies and equipment required for training, pilot testing, fieldwork, sample transport, and laboratory analysis depend on the method of data collection and the selection of biomarkers and food nutrients.
Module 9: Survey equipment and supplies provides more detailed information and links to tools to help plan for specific survey supply and equipment needs. The “Equipment and Supplies List (single worksheet)” online tool can be used to work out a rough calculation of the supplies, equipment and associated budget needed for the proposed number and type of field and laboratory tests.
Managing the logistics of training and fieldwork, along with the appropriate storage of specimens and samples, is complex and includes determining:
- the number of teams and the team size and composition;
- the training agenda, including details on a pilot field test of all procedures, with proposed location and accommodations;
- the process and training required for mapping and household listing or other sampling procedures;
- transportation of:
- Field staff and supervisors
- Field supplies and equipment
- Questionnaires (where paper-based), specimens and samples from survey sites to the appropriate place for management and analysis;
- storage and cold chain facilities for samples and specimens;
- maintenance and charging of electronic devices, where used, and;
- community mobilization strategies.
There are numerous examples of survey questionnaires, some of which can be adapted to meet specific survey objectives. Module 11, Data collection tools, field manual, and database, includes detailed guidance on developing and testing the main survey questionnaire. Questionnaires also need to collect information to meet the needs of secondary data requirements such as:
- Indicators of household wealth/vulnerability to poverty
- Intervention-related factors, for example, household access to a fortifiable or fortified product
- Cultural or environmental factors that may affect micronutrient status, for example, specific dietary choices or the use of insecticide-treated nets to protect against malaria infection.
Data management, reporting, and dissemination
The data management section of the survey protocol should include plans for initial data entry (if paper-based data collection), data processing, data weighting, analysis and presentation of results. A Data manager is a necessary and important member of the survey team and Technical committee. Module 14, Data entry and cleaning, and Module 15, Data processing and analysis provide detailed guidance on the process of and personnel requirements for data management and analysis.
Reporting and dissemination are critical components of the overall survey. Plans for report preparation, printing and distribution, and for dissemination events, should be defined early on to ensure that the end product will meet the objectives and procedures agreed by stakeholders and to inform the budget and timeline. The report formats and an outline of their content should also be agreed. Module 16, Survey reports and dissemination provides details on aspects to consider in planning these activities.
Budget and timeline
The budget and timeline are key to guiding survey implementation. They must be realistic and allow for unexpected costs and delays. The Survey manager and the Technical committee need to consider all the issues and factors that might affect them, including timing (for example, any holidays or periods during which much of the population may be working away from their usual place of residence) and budget (for example, an increase in fuel prices).
Module 10, Budget and timeline provides detailed guidance on planning survey budgets and timelines. The ”Generic budget” and “Generic timeline” online tools may be useful to develop a rough calculation of the budget and timelines required for all survey components.
At this point in the planning process, it is useful to develop a brief concept note covering the main points of the survey (objectives, design, and estimated timeline and budget). An example can be found in the “Micronutrient survey concept note” online tool.