Operational definition

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The term operational definition or operationalization of a characteristic goes back to Bridgman (1927). The original, on the physics tailored version tries to experience concepts to make empirically measurable.


If, for example, it is to be measured how many drivers can drive “well”, it must first be determined what exactly is meant by the term “drive well”. Because every person has a certain idea of ​​"good", but it is not clear what this qualitative statement means if you want to make it empirically tangible.

The problem here is that a concept of experience, which does not have to be defined in more detail in everyday life, is not sufficient for a scientific statement in this form, since every person uses a different concept of experience. Therefore, “ variables ” or “indicators”, ie a characteristic of an object of investigation that exists in different forms, are defined first, which can be described as mental or physical operators of the facts identified by the term. In this case, the operators “prudent”, “adhering to the speed limit” or similar could be specified. Under the operationalization one now understands the steps of assigning empirically detectable, observable or erfragenden indicators to a theoretical concept. Through operationalization, measurements of the empirical phenomena identified by a term become possible and understandable for people who are not identical with the definer.

Importance in physics

Bortz-Döring sums up the variant of the operational definition found in physics as follows: “1. The operational definition is synonymous with a corresponding set of operations […] 2. A term should not be defined in terms of its properties, but in terms of the operations associated with it . 3. The true meaning of the term is not found by observing what you say about it, but by noting what you do with it. 4. All of our knowledge is to be put into perspective against operations selected to measure our scientific concepts. If there are several sets of operations, they are also based on several concepts. "

Importance in the social sciences

In the social sciences, the relationship between the theoretical concept and the operational definition poses a particular problem:

a) The term can be "under-defined"; H. the term is then reduced in content to compliance with the measurement rule.

b) The term is "over-defined"; H. the term still resonates with nuances of meaning that are not even covered by its measurement rules.

In case (b) the operational definition is overwhelmed by its use within a theory; because it is used to make statements that it cannot objectively make. This puts the validity or validity of the indicators in question.

For the purpose of operationalization, measurement rules must be specified. They either indicate the conditions under which a qualitatively defined characteristic can be ascribed to a situation ( categorization ). Or if such attributable characteristics are quantifiable, a scale with units of measurement for measured quantities ( dimensions ) is indicated, whereby a certain measured quantity (i.e. a numerical value) can be assigned to each fact that can be described in this way. Such quantifiable characteristics are also referred to in abbreviated form as variables .

Concern of the operational definition

Overall, the operational definition tries to enable theoretical or abstract terms, which basically cannot be measured directly, to be measured by assigning indicators. The original term is broken down into individual variables here in order to obtain a basis for the measurement. In doing so, disposition terms are often used that describe properties that are not recognizable through direct observation, but are linked to certain test conditions, which is why most definitions are referred to as partial, for example the term "fat-soluble": The fat solubility can only be proven by experiment become. Here the precondition represents an operation with which the property to be defined can be checked (see operationalization ).


An operational definition is such a precisely defined concept of experience that it is possible to make judgments about observations, for example about a sentence like "This person is a very good / good / ... / bad / very bad driver".

Individual evidence

  1. ^ PW Bridgman: The Logic of Modern Physics. MacMillian, New York 1927 (German translation: PW Bridgman: The logic of today's physics. Hueber, Munich 1932).
  2. Peter Atteslander , Methods of Empirical Social Research, Berlin: de Gruyter, 2000, 9., revised. and exp. Ed., P. 50.
  3. Jürgen L. Rößler: The operational definition. Peter Lang, Frankfurt a. M. 1998.
  4. J. Bortz, N. Döring, Research Methods and Evaluation for Human and Social Scientists. Springer, Heidelberg 2006, ISBN 3-540-33305-3 , pp. 60–63 ( limited preview in Google book search).
  5. ^ Paul Feyerabend : The problem of the existence of theoretical entities. In: Ernst Topitsch (ed.): Problems of the philosophy of science. Festschrift for Viktor Kraft. Vienna 1960.