The most important figures that one needs for management are unknown or unknowable.
An operational definition is a procedure agreed upon for translation of concept into measurement of some kind.
If you change the rule for counting people, you come up with a new number.
It is wrong to suppose that if you can’t measure it, you can’t manage it – a costly myth.
Data are not taken for museum purposes; they are taken as a basis for doing something. If nothing is to be done with the data, then there is no use in collecting any. The ultimate purpose of taking data is to provide a basis for action or a recommendation for action. The step intermediate between the collection of data and the action is prediction.