2.1 Sampling Frames for Agricultural Probability Sample Surveys

There are two basic types of sampling frames used for the last-stage of selection of an agricultural probability sample survey: area frames and list frames.

The sampling units of an area frame are land areas called segments, and the selection probability of each segment is proportional to its area measure. The sampling units of a list frame are usually the holdings or holders addresses.

Therefore, there are two basic types of sample designs in terms of the last-stage sampling unit and the rules to assign their probabilities of selection, namely area sample designs and list sample designs, also known as area frame sample surveys and list frame sample surveys.

Multiple frame surveys are those agricultural probability sample designs that combine more than one sample design to obtain the survey estimates, combining area frame designs with list frame designs. A multiple frame survey usually consists of an area sample component and a list sample component.

Consequently, agricultural probability sample surveys can be classified as follows:

For the current agricultural probability sample surveys considered, it will be assumed that most data will be obtained by enumerators through personal interviews in the field. Indeed, other means of periodic data collection, for example the use of self-administered questionnaires, mail, telephone inquiries, or extraction of information from registers are usually not feasible in developing countries.

The field data collection of an agricultural survey may include or not, in the selected sampling units, expert observation or identification and objective measurement of crop areas or other agricultural characteristics of special interest.