Vandervert (1980/1988) described in scientific detail a simple, everyday illustration of an operational definition in terms of making a cake (i.e., its recipeis an operational definition used in a specialized laboratory known as the household kitchen) .Vandervert, L. (1988). Operational definitions made simple, useful, and lasting. In M. Ware & C. Brewer (Eds.), Handbook for teaching statistics and research methods (pp. 132–134). Hillsdale, NJ: Lawrence Erlbaum Associates. (Original work published 1980) Similarly, the saying, if it walks like a duck and quacks like a duck, it must be some kind of duck, may be regarded as involving a sort of measurement process or set of tests (see duck test).
A cake can be operationally defined by a cake recipe .Vandervert, L. (1988). Operational definitions made simple, useful, and lasting. In M. Ware & C. Brewer (Eds.), Handbook for teaching statistics and research methods (pp. 132–134). Hillsdale, NJ: Lawrence Erlbaum Associates. (Original work published 1980) 
R
Vandervert (1980/1988) described in scientific detail a simple, everyday illustration of an operational definition in terms of making a cake (i.e., its recipeis an operational definition used in a specialized laboratory known as the household kitchen)
A cake can be operationally defined by a cake recipe
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Similarly, the saying, if it walks like a duck and quacks like a duck, it must be some kind of duck, may be regarded as involving a sort of measurement process or set of tests (see duck test).