Define sampling frame.

• A. The list of elements from which a sample is drawn.
• B. The method used to select participants.
• C. The randomization protocol.
• D. The target population.

Answer: (A)

A sampling frame is the list of elements from which a sample is drawn. It is the actual source material for selecting units to study and should mirror the population of interest as closely as possible. If important members are missing from the frame, or if the frame includes elements outside the population, bias can occur because those elements have no chance of being selected or are overrepresented. For example, studying all high school seniors in a district using the district’s official senior enrollment roster as the frame is appropriate, but homeschooled seniors or recent movers not on that roster would be excluded. The frame also matters for calculating selection probabilities when using probability sampling. The other concepts describe how you choose participants, the randomness used, or the group you want to study, not the actual source list used to draw the sample.