What are the test sample and the reference sample?

The reference sample is usually from a proven product or process. For example, the reference sample in pharmaceutical studies is often from a drug that was evaluated extensively and was proven to have the desired effect.

The test sample is often from a newer product or process. For example, the test sample in pharmaceutical studies is often from a new generic drug. You might use an equivalence test to determine whether the generic drug is as effective as the reference drug.