Sampling Frame

A sampling frame is the concrete list of units from which a sample is selected: a student enrollment register, a membership database, a directory of firms, or a list of email addresses. It is the practical bridge between the abstract population and the actual sample. An ideal frame includes every member of the population exactly once, with no outsiders. In practice, frames are imperfect: they miss some members, include ineligible cases, or contain duplicates, and these gaps create coverage error.

For a thesis, naming your sampling frame shows examiners exactly how you moved from population to sample. It also forces you to confront who was excluded before sampling even began. Discussing frame limitations, such as members without email access or outdated records, strengthens your limitations section and protects your conclusions from an easy line of criticism.