An issue to be resolved early in the planning of a field trial is whether the study participants should be seen at a central location, at a series of local assembly points, or be visited on a house-to-house basis. The decision will depend upon the procedures to be carried out, the nature of equipment required, the time the study procedures take, the population size, density, and distribution, and the environmental and physical conditions.
A central assembly point may be most efficient for the study team, since more people can be seen in a day than in a house-to-house survey. If heavy or delicate non-portable equipment must be used, then a central assembly point cannot be avoided. Even if some of the data collection or physical or laboratory examinations have to be done at a central location, it is often advisable to conduct the census, and sometimes questionnaire interviews, at the houses of participants.
One advantage of a house-to-house survey is that it is possible to be reasonably sure of being able to compile a list of most of those who are eligible for the trial. Any persons who do not report to a central assembly point can then be identified, and, if necessary, attempts made to find them. Individuals who are not present during the home visit might be able to attend the central assembly point at another time. Tracing those missing can be costly and time-consuming, and decisions about the benefits of doing this, as compared to the time and effort required to visit individual households, need to be considered in the planning phase. Also, the likely magnitude of ‘non-response’ may need to be estimated during the pilot phase (see Chapter 13). Sometimes, a combination of both approaches may be suitable, whereby someone visits each household to conduct a household census and identifies all potentially eligible individuals who are given an appointment to go to a central location for the actual data collection.
Careful planning of the physical layout for the flow of people from one part of the field station to the next is important. Special attention may have to be given for carrying out the physical examination, in order to ensure both privacy and adequate light. Usually, there is little difficulty about making such arrangements when the examinations are conducted at a central assembly point, but, for more mobile surveys, special arrangements may be necessary, ranging from simple screening under a shady tree to the use of a tent with special lighting.
In addition to whatever arrangements are made for the interviewing, examinations, and specimen collection from study subjects, there are supporting functions that will require physical facilities. These include a headquarters for administration; a room for team training courses, meetings, and review of activities and problems on a daily basis; space for computer processing of data; file storage space; laboratory accommodation; stores for equipment and supplies; and transport garaging. The various components may be needed at one place or at several places or may need to be mobile.
If the field team must live away from home for long periods, they may be able to obtain local accommodation, but other accommodation might have to be provided (for example, tents). Accommodation and cooking facilities should be arranged in advance, and employment of a cook will save on staff time and improve staff morale (if the cook is good!). Food may need careful storage and cooking, in order to avoid food poisoning. Water for drinking may need to be purified, filtered, or boiled. Refuse disposal and toilets may also be needed.
Where the field teams will use electrical equipment for their activities, a reliable source of electricity will be required. Even if there is a normally reliable local electricity supply, some form of backup supply should be considered. In some cases, using solar power or project vehicles to charge equipment may be sufficient, though it is usually wise to have an additional backup source such as a portable generator. In some places, there will be no local mains electricity, and then it is essential for the team to have their own electricity supply and strongly advisable to have a backup for that too in case of malfunction. Similarly, ease of access to the Internet and the quality and extent of mobile phone network coverage should be taken into account if field teams will be expected to communicate with headquarters in these ways.