An operational definition specifies concrete, replicable procedures designed to represent a construct. In the words of American psychologist S.S. Stevens (1935), "An operation is the performance which we execute in order to make known a concept." For example, an operational
definition
A definition is a statement of the meaning of a term (a word, phrase, or other set of symbols). Definitions can be classified into two large categories: intensional definitions (which try to give the sense of a term), and extensional definitio ...
of "fear" (the construct) often includes measurable physiologic responses that occur in response to a perceived threat. Thus, "fear" might be operationally defined as specified changes in heart rate, galvanic skin response, pupil dilation, and blood pressure.
Overview
An operational definition is designed to model or represent a concept or
theoretical definition
A theoretical definition defines a term in an academic discipline, functioning as a proposal to see a phenomenon in a certain way. A theoretical definition is a proposed way of thinking about potentially related events. Theoretical definitions cont ...
, also known as a construct. Scientists should describe the operations (procedures, actions, or processes) that define the concept with enough specificity such that other investigators can replicate their research.
Operational definitions are also used to define system states in terms of a specific, publicly accessible process of preparation or validation testing. For example, 100 degrees Celsius may be operationally defined as the process of heating water at sea level until it is observed to boil.
A cake can be operationally defined by a cake recipe.
Application
Despite the controversial
philosophical
Philosophy (from , ) is the systematized study of general and fundamental questions, such as those about existence, reason, knowledge, values, mind, and language. Such questions are often posed as problems to be studied or resolved. Some ...
origins of the concept, particularly its close association with
logical positivism
Logical positivism, later called logical empiricism, and both of which together are also known as neopositivism, is a movement in Western philosophy whose central thesis was the verification principle (also known as the verifiability criterion o ...
, operational definitions have undisputed practical applications. This is especially so in the social and medical sciences, where operational definitions of key terms are used to preserve the unambiguous empirical testability of hypothesis and theory. Operational definitions are also important in the
physical sciences
Physical science is a branch of natural science that studies non-living systems, in contrast to life science. It in turn has many branches, each referred to as a "physical science", together called the "physical sciences".
Definition
Phy ...
.
Philosophy
The ''Stanford Encyclopedia of Philosophy'' entry on scientific realism, written by
Richard Boyd
Richard Newell Boyd (May 19, 1942 – February 20, 2021) was an American philosopher, who spent most of his career teaching philosophy at Cornell University where he was Susan Linn Sage Professor of Philosophy and Humane Letters Emeritus. He speci ...
, indicates that the modern concept owes its origin in part to
Percy Williams Bridgman
Percy Williams Bridgman (April 21, 1882 – August 20, 1961) was an American physicist who received the 1946 Nobel Prize in Physics for his work on the physics of high pressures. He also wrote extensively on the scientific method and on other as ...
, who felt that the expression of scientific concepts was often abstract and unclear. Inspired by
Ernst Mach
Ernst Waldfried Josef Wenzel Mach ( , ; 18 February 1838 – 19 February 1916) was a Moravian-born Austrian physicist and philosopher, who contributed to the physics of shock waves. The ratio of one's speed to that of sound is named the Mach ...
, in 1914 Bridgman attempted to redefine unobservable entities concretely in terms of the physical and mental operations used to measure them. Accordingly, the definition of each unobservable entity was uniquely identified with the instrumentation used to define it. From the beginning objections were raised to this approach, in large part around the inflexibility. As Boyd notes, "In actual, and apparently reliable, scientific practice, changes in the instrumentation associated with theoretical terms are routine. and apparently crucial to the progress of science. According to a 'pure' operationalist conception, these sorts of modifications would not be methodologically acceptable, since ''each'' definition must be considered to identify a ''unique'' 'object' (or class of objects)." However, this rejection of operationalism as a general project destined ultimately to define all experiential phenomena uniquely did not mean that operational definitions ceased to have any practical use or that they could not be applied in particular cases.
Science
The
special theory of relativity
In physics, the special theory of relativity, or special relativity for short, is a scientific theory regarding the relationship between Spacetime, space and time. In Albert Einstein's original treatment, the theory is based on two Postulates of ...
can be viewed as the introduction of operational definitions for simultaneity of events and of
distance
Distance is a numerical or occasionally qualitative measurement of how far apart objects or points are. In physics or everyday usage, distance may refer to a physical length or an estimation based on other criteria (e.g. "two counties over"). ...
, that is, as providing the operations needed to define these terms.
In
quantum mechanics
Quantum mechanics is a fundamental theory in physics that provides a description of the physical properties of nature at the scale of atoms and subatomic particles. It is the foundation of all quantum physics including quantum chemistry, ...
the notion of operational definitions is closely related to the idea of
observables
In physics, an observable is a physical quantity that can be measured. Examples include position and momentum. In systems governed by classical mechanics, it is a real-valued "function" on the set of all possible system states. In quantum physi ...
, that is, definitions based upon what can be measured.
Operational definitions are often most challenging in the fields of
psychology
Psychology is the scientific study of mind and behavior. Psychology includes the study of conscious and unconscious phenomena, including feelings and thoughts. It is an academic discipline of immense scope, crossing the boundaries betwe ...
and
psychiatry
Psychiatry is the medical specialty devoted to the diagnosis, prevention, and treatment of mental disorders. These include various maladaptations related to mood, behaviour, cognition, and perceptions. See glossary of psychiatry.
Initial psych ...
, where intuitive concepts, such as
intelligence
Intelligence has been defined in many ways: the capacity for abstraction, logic, understanding, self-awareness, learning, emotional knowledge, reasoning, planning, creativity, critical thinking, and problem-solving. More generally, it can b ...
need to be operationally defined before they become amenable to scientific investigation, for example, through processes such as
IQ test
An intelligence quotient (IQ) is a total score derived from a set of standardized tests or subtests designed to assess human intelligence. The abbreviation "IQ" was coined by the psychologist William Stern (psychologist), William Stern for th ...
s.
Business
On October 15, 1970, the
West Gate Bridge
The West Gate Bridge is a steel, box girder, cable-stayed bridge in Melbourne, Victoria, Australia, spanning the Yarra River just north of its mouth into Port Phillip. It carries the West Gate Freeway and is a vital link between the inner ci ...
in
Melbourne
Melbourne ( ; Boonwurrung/Woiwurrung: ''Narrm'' or ''Naarm'') is the capital and most populous city of the Australian state of Victoria, and the second-most populous city in both Australia and Oceania. Its name generally refers to a met ...
,
Australia
Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...
collapsed, killing 35 construction workers. The subsequent enquiry found that the failure arose because engineers had specified the supply of a quantity of ''flat steel plate.'' The word ''flat'' in this context lacked an operational definition, so there was no test for accepting or rejecting a particular shipment or for controlling quality.
In his managerial and statistical writings,
W. Edwards Deming
William Edwards Deming (October 14, 1900 – December 20, 1993) was an American engineer, statistician, professor, author, lecturer, and management consultant. Educated initially as an electrical engineer and later specializing in mathematical ...
placed great importance on the value of using operational definitions in all agreements in business. As he said:
::"An operational definition is a procedure agreed upon for translation of a concept into measurement of some kind." – W. Edwards Deming
::"There is no true value of any characteristic, state, or condition that is defined in terms of measurement or observation. Change of procedure for measurement (change of operational definition) or observation produces a new number." – W. Edwards Deming
General process
Operational, in a process context, also can denote a working method or a philosophy that focuses principally on cause and effect relationships (or stimulus/response, behavior, etc.) of specific interest to a particular domain at a particular point in time. As a working method, it does not consider issues related to a domain that are more general, such as the
ontological
In metaphysics, ontology is the philosophical study of being, as well as related concepts such as existence, becoming, and reality.
Ontology addresses questions like how entities are grouped into categories and which of these entities exis ...
, etc.
In computing
Science uses computing. Computing uses science. We have seen the development of computer science. There are not many who can bridge all three of these. One effect is that, when results are obtained using a computer, the results can be impossible to replicate if the code is poorly documented, contains errors, or if parts are omitted entirely.
Many times, issues are related to persistence and clarity of use of variables, functions, and so forth. Also, systems dependence is an issue. In brief, length (as a standard) has matter as its definitional basis. What pray tell can be used when standards are to be computationally framed?
Hence, operational definition can be used within the realm of the interactions of humans with advanced computational systems. In this sense, one area of discourse deals with computational thinking in, and with how it might influence, the sciences. To quote the American Scientist:
* The computer revolution has profoundly affected how we think about science, experimentation, and research.
One referenced project pulled together fluid experts, including some who were expert in the numeric modeling related to computational fluid dynamics, in a team with computer scientists. Essentially, it turned out that the computer guys did not know enough to weigh in as much as they would have liked. Thus, their role, to their chagrin, many times was "mere" programmer.
Some
knowledge-based engineering
Knowledge-based engineering (KBE) is the application of knowledge-based systems technology to the domain of manufacturing design and production. The design process is inherently a knowledge-intensive activity, so a great deal of the emphasis for K ...
projects experienced similarly that there is a trade-off between trying to teach programming to a domain expert versus getting a programmer to understand the intricacies of a domain. That, of course, depends upon the domain. In short, any team member has to decide which side of the coin to spend one's time.
The International Society for Technology in Education has a brochure detailing an "operational definition" of computational thinking. At the same time, the ISTE made an attempt at defining related skills.
A recognized skill is tolerance for ambiguity and being able to handle open-ended problems. For instance, a
knowledge-based engineering
Knowledge-based engineering (KBE) is the application of knowledge-based systems technology to the domain of manufacturing design and production. The design process is inherently a knowledge-intensive activity, so a great deal of the emphasis for K ...
system can enhance its operational aspect and thereby its stability through more involvement by the
subject-matter expert
A subject-matter expert (SME) is a person who has authority, accumulated great knowledge in a particular field or topic and this level of knowledge is demonstrated by the person's degree, licensure, and/or through years of professional experience ...
, thereby opening up issues of limits that are related to being human. As in, many times, computational results have to be taken at face value due to several factors (hence the duck test's necessity arises) that even an expert cannot overcome. The end proof may be the final results (reasonable facsimile by
simulation
A simulation is the imitation of the operation of a real-world process or system over time. Simulations require the use of Conceptual model, models; the model represents the key characteristics or behaviors of the selected system or proc ...
or artifact, working design, etc.) that are not guaranteed to be repeatable, may have been costly to attain (time and money), and so forth.
In advanced modeling, with the requisite computational support such as knowledge-based engineering, mappings must be maintained between a real-world object, its abstracted counterparts as defined by the domain and its experts, and the computer models. Mismatches between domain models and their computational mirrors can raise issues apropos this topic. Techniques that allow the flexible modeling required for many hard problems must resolve issues of identity, type, etc. which then lead to methods, such as duck typing. Many domains, with a numerics focus, use limit theory, of various sorts, to overcome the duck test necessity with varying degrees of success. Yet, with that, issues still remain as representational frameworks bear heavily on what we can know.
In arguing for an object-based methodology, Peter Wegner suggested that "positivist scientific philosophies, such as operationalism in
physics
Physics is the natural science that studies matter, its fundamental constituents, its motion and behavior through space and time, and the related entities of energy and force. "Physical science is that department of knowledge which r ...
and behaviorism in psychology" were powerfully applied in the early part of the 20th century. However, computation has changed the landscape. He notes that we need to distinguish four levels of "irreversible physical and computational abstraction" (Platonic abstraction, computational approximation, functional abstraction, and value computation). Then, we must rely on interactive methods, that have behavior as their focus (see duck test).
Examples
Temperature
The thermodynamic definition of
temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer.
Thermometers are calibrated in various temperature scales that historically have relied o ...
, due to Nicolas Léonard Sadi Carnot, refers to heat "flowing" between "infinite reservoirs". This is all highly abstract and unsuited for the day-to-day world of science and trade. In order to make the idea concrete, temperature is defined in terms of operations with the gas thermometer. However, these are sophisticated and delicate instruments, only adapted to the national standardization laboratory.
For day-to-day use, the International Temperature Scale of 1990 (ITS) is used, defining temperature in terms of characteristics of the several specific sensor types required to cover the full range. One such is the
electrical resistance
The electrical resistance of an object is a measure of its opposition to the flow of electric current. Its reciprocal quantity is , measuring the ease with which an electric current passes. Electrical resistance shares some conceptual parallels ...
of a
thermistor
A thermistor is a type of resistor whose resistance is strongly dependent on temperature, more so than in standard resistors. The word thermistor is a portmanteau of ''thermal'' and ''resistor''.
Thermistors are divided based on their conduction ...
, with specified construction,
calibrated
In measurement technology and metrology, calibration is the comparison of measurement values delivered by a device under test with those of a calibration standard of known accuracy. Such a standard could be another measurement device of known ...
against operationally defined fixed points.
Electric current
Electric current
An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving pa ...
is defined in terms of the
force
In physics, a force is an influence that can change the motion of an object. A force can cause an object with mass to change its velocity (e.g. moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a p ...
between two
infinite
Infinite may refer to:
Mathematics
* Infinite set, a set that is not a finite set
*Infinity, an abstract concept describing something without any limit
Music
*Infinite (group), a South Korean boy band
*''Infinite'' (EP), debut EP of American m ...
parallel
Parallel is a geometric term of location which may refer to:
Computing
* Parallel algorithm
* Parallel computing
* Parallel metaheuristic
* Parallel (software), a UNIX utility for running programs in parallel
* Parallel Sysplex, a cluster of ...
conductors, separated by a specified distance. This definition is too abstract for practical measurement, so a device known as a current balance is used to define the
ampere
The ampere (, ; symbol: A), often shortened to amp,SI supports only the use of symbols and deprecates the use of abbreviations for units. is the unit of electric current in the International System of Units (SI). One ampere is equal to elect ...
operationally.
Mechanical hardness
Unlike
temperature
Temperature is a physical quantity that expresses quantitatively the perceptions of hotness and coldness. Temperature is measured with a thermometer.
Thermometers are calibrated in various temperature scales that historically have relied o ...
and
electric current
An electric current is a stream of charged particles, such as electrons or ions, moving through an electrical conductor or space. It is measured as the net rate of flow of electric charge through a surface or into a control volume. The moving pa ...
, there is no abstract physical concept of the
hardness
In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, different materials differ in their hardness; for example hard ...
of a material. It is a slightly vague, subjective idea, somewhat like the idea of
intelligence
Intelligence has been defined in many ways: the capacity for abstraction, logic, understanding, self-awareness, learning, emotional knowledge, reasoning, planning, creativity, critical thinking, and problem-solving. More generally, it can b ...
. In fact, it leads to three more specific ideas:
# Scratch hardness measured on Mohs' scale;
# Indentation hardness; and
# Rebound, or dynamic, hardness measured with a Shore
scleroscope
A scleroscope is a device used to measure rebound hardness
In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, di ...
.
Of these, indentation hardness itself leads to many operational definitions, the most important of which are:
#
Brinell hardness test
The Brinell scale characterizes the indentation hardness of materials through the scale of penetration of an indenter, loaded on a material test-piece. It is one of several definitions of hardness in materials science.
History
Proposed by Swe ...
– using a 10 mm steel ball;
#
Vickers hardness test
The Vickers hardness test was developed in 1921 by Robert L. Smith and George E. Sandland at Vickers Ltd as an alternative to the Brinell method to measure the hardness of materials. The Vickers test is often easier to use than other hardness t ...
– using a pyramidal diamond indenter; and
#
Rockwell hardness test
The Rockwell scale is a hardness scale based on indentation hardness of a material. The Rockwell test measures the depth of penetration of an indenter under a large load (major load) compared to the penetration made by a preload (minor load). The ...
– using a diamond cone indenter.
In all these, a process is defined for loading the indenter, measuring the resulting indentation, and calculating a hardness number. Each of these three sequences of measurement operations produces numbers that are consistent with our subjective idea of hardness. The harder the material to our informal perception, the greater the number it will achieve on our respective hardness scales. Furthermore, experimental results obtained using these measurement methods has shown that the hardness number can be used to predict the stress required to permanently deform steel, a characteristic that fits in well with our idea of resistance to permanent deformation. However, there is not always a simple relationship between the various hardness scales. Vickers and Rockwell hardness numbers exhibit qualitatively different behaviour when used to describe some materials and phenomena.
The constellation Virgo
The constellation Virgo is a specific constellation of stars in the sky, hence the process of forming Virgo cannot be an operational definition, since it is historical and not repeatable. Nevertheless, the process whereby we locate Virgo in the sky ''is'' repeatable, so in this way, Virgo is operationally defined. In fact, Virgo can have any number of definitions (although we can never prove that we are talking about the ''same'' Virgo), and any number may be operational.
Academic discipline
New
academic discipline
An academy ( Attic Greek: Ἀκαδήμεια; Koine Greek Ἀκαδημία) is an institution of secondary or tertiary higher learning (and generally also research or honorary membership). The name traces back to Plato's school of philosophy ...
s appear in response to
interdisciplinary
Interdisciplinarity or interdisciplinary studies involves the combination of multiple academic disciplines into one activity (e.g., a research project). It draws knowledge from several other fields like sociology, anthropology, psychology, ec ...
activity at universities. An academic suggested that a subject matter area becomes a discipline when there are more than a dozen university departments using the same name for roughly the same subject matter.
Rustum Roy
Rustum Roy (July 3, 1924 – August 26, 2010) was a physicist, born in India, who became a professor at Pennsylvania State University and was a leader in materials research. As an advocate for interdisciplinarity, he initiated a movement of mat ...
(1977) "Interdisciplinary science on campus – the elusive dream",
Chemical and Engineering News
''Chemical & Engineering News'' (''C&EN'') is a weekly news magazine published by the American Chemical Society, providing professional and technical news and analysis in the fields of chemistry and chemical engineering.Duck test
*
Operationalization
In research design, especially in psychology, social sciences, life sciences and physics, operationalization or operationalisation is a process of defining the measurement of a phenomenon which is not directly Measurement, measurable, though its ex ...
*
Pragmatic maxim {{C. S. Peirce articles, abbreviations=no
The pragmatic maxim, also known as the maxim of pragmatism or the maxim of pragmaticism, is a maxim of logic formulated by Charles Sanders Peirce. Serving as a normative recommendation or a regulative princ ...
*
Pragmaticism
"Pragmaticism" is a term used by Charles Sanders Peirce for his pragmatic philosophy starting in 1905, in order to distance himself and it from pragmatism, the original name, which had been used in a manner he did not approve of in the "literary j ...
*
Pragmatism
Pragmatism is a philosophical tradition that considers words and thought as tools and instruments for prediction, problem solving, and action, and rejects the idea that the function of thought is to describe, represent, or mirror reality. ...
* Ballantyne, Paul F. ''History and Theory of Psychology Course, in'' Langfeld, H.S. (1945). Introduction to the Symposium on Operationism. ''Psyc. Rev.'' 32, 241–24 * Bohm, D. (1996). On Dialog. N.Y.: Routledge.
* Boyd, Richard. (1959).''On the Current Status of the Issue of Scientific Realism'' in ''Erkenntnis''. 19, 45–90.
* Bridgman, P. W. ''The way things are.'' Cambridge: Harvard University Press.
* Carnap, Rudolph. (1959). ''The Elimination of Metaphysics Through Logical Analysis of Language'' in Ayer, A.J.
* Churchland, Patricia. (1986). ''Neurophilosophy— Toward a unified science of the mind/brain,'' MIT Press.
* Churchland, Paul. (1989). ''A Neurocomputational Perspective— The Nature of Mind and the Structure of Science,'' MIT Press.
* Dennett, Daniel C. (1992).''Consciousness Explained'', Little, Brown & Co..
* Depraz, N. (1999). "The phenomenological reduction as praxis." ''Journal of Consciousness Studies'', 6(2-3), 95–110.
* Green, C. D. (1992). "Of Immortal Mythological Beasts: Operationism in Psychology." ''Theory & Psychology'', 2, 291–32 * Hardcastle, G. L. (1995). "S.S. Stevens and the origins of operationism." ''Philosophy of Science'', 62, 404–424.
* Hermans, H. J. M. (1996). "Voicing the self: from information processing to dialogical interchange." ''Psychological Bulletin'', 119(1), 31–50.
* Hyman, Bronwen, U of Toronto, and Shephard, Alfred H., U of Manitoba. (1980). "Zeitgeist: The Development of an Operational Definition", ''The Journal of Mind and Behavior'', 1(2), 227–246.
* Leahy, Thomas H., Virginia Commonwealth U. (1980). ''The Myth of Operationism,'' ''ibid,'', 127–144.
* Ribes-Inesta, Emilio "What Is Defined In Operational Definitions? The Case Of Operant Psychology," ''Behavior and Philosophy'', 200 * Roepstorff, A. & Jack, A. (2003). "Editorial introduction, Special Issue: Trusting the Subject? (Part 1)." ''Journal of Consciousness Studies'', 10(9–10), v–xx.
* Roepstorff, A. & Jack, A. (2004). "Trust or Interaction? Editorial introduction, Special Issue: Trusting the Subject? (Part 2)." ''Journal of Consciousness Studies'', 11(7–8), v–xxii.
* Stevens, S. S. (1963).''Operationism and logical positivism, in'' M. H. Marx (Ed.), Theories in contemporary psychology (pp. 47–76). New York: MacMillan.
* Thomson — Waddsworth, eds., ''Learning Psychology: Operational Definitions Research Methods Workshops
{{Defining
DefinitionPhilosophy of science