[…] each test is a combination of treatment, subject and object. […] Example: A test can be that one person (subject) uses the new development method (treatment) for developing program A (object).

Wohlin, C., Runeson, P., Höst, M., Ohlsson, M., Regnell, B., & Wesslén, A. (2000). Introduction to Experimentation in Software Engineering. [-]