Sampling Frame
The actual, tangible list or source material from which the sample is drawn.
What is Sampling Frame?
While the population is a theoretical construct (everyone who meets the criteria), the sampling frame is the practical mechanism used to reach them. It is the definitive list (e.g., a registry, a database, a directory) of population members from which the researcher will randomly select their sample.
Why Sampling Frame Matters
The quality of probability sampling depends entirely on the accuracy of the sampling frame. If the frame is outdated, incomplete, or includes ineligible members, it introduces 'sampling frame error,' which biases the results before data collection even begins.
Example
In a study of registered voters in a county, the population is all eligible voters. The sampling frame is the official, updated county voter registration database provided by the election board.
Common Mistakes
- Assuming the sampling frame perfectly matches the target population (e.g., using a phone directory as a frame, ignoring those without listed numbers).
- Failing to account for or clean the sampling frame of duplicates or deceased individuals before drawing the random sample.