In statistics, a sampling frame is the source material or device from which a sample is drawn. It is a list of all those within a population who can be sampled, and may include individuals, households or institutions.
In many practical situations, the frame is a matter of choice to the survey planner, and sometimes a critical one.
a) Qualities of sample frame
An ideal sampling frame will have the following qualities:
- All units have a logical, numerical identifier.
- All units can be found -their contact information, map location, other relevant information is present.
- The frame is organized in a logical, systematic fashion.
- The frame has additional information about the units that allow the use of more advanced sampling frames.
- Every element of the population of interest is present in the frame.
- Every element of the population is present only once in the frame.
- No elements from outside the population of interest are present in the frame
- The data is 'up-to-date'.
b) Sample frames problems
- Some members of the population are may not be included in the frame.
- The non-members of the population may be included in the frame.
- Duplicate entries. A member of the population is surveyed more than once.
- Groups or clusters.