Operationalism

the doctrine that the meaning of a proposition consists of the operations involved in proving or applying it

http://www.wordreference.com/definition/operationalism

http://www.thefreedictionary.com/operationalism

http://www.philosophyprofessor.com/philosophies/operationalism.php

<http://www.une.edu.au/Web Stat/unit_materials/c2_research_design/operationalism.htm> (nice long discussion, but has some bits which I think are pretty misleading)