Working hypothesis

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A working hypothesis is a hypothesis that is provisionally accepted as a basis for further ongoing research [1] in the hope that a tenable theory will be produced, even if the hypothesis ultimately fails. [2] Like all hypotheses, a working hypothesis is constructed as a statement of expectations, which can be linked to deductive, exploratory research [3] [4] in empirical investigation and is often used as a conceptual framework in qualitative research. [5] [6] The term "working" indicates that the hypothesis is subject to change. [3]

Contents

History

Use of the phrase "working hypothesis" goes back to at least the 1850s. [7]

Charles Sanders Peirce came to hold that an explanatory hypothesis is not only justifiable as a tentative conclusion by its plausibility (by which he meant its naturalness and economy of explanation), [8] but also justifiable as a starting point by the broader promise that the hypothesis holds for research. This idea of justifying a hypothesis as potentially fruitful (at the level of research method), not merely as plausible (at the level of logical conclusions), is essential for the idea of a working hypothesis, as later elaborated by Peirce's fellow pragmatist John Dewey.

In 1890, [9] and again in 1897, [10] Thomas Chrowder Chamberlin wrote "The method of multiple working hypotheses", in which he advocated the importance of simultaneously evaluating several hypotheses, rejecting those that conflict with available data, and ending with the one hypothesis supported by the data. This stood in contrast to what he called the single ruling theory, which encouraged scientists to find supporting data and not challenge it with difficult tests. The paper is considered a landmark [11] on the scientific method, was an inspiration for the approach called strong inference, and was reprinted in 1965. [12]

Peirce held that, as a matter of research method, an explanatory hypothesis is judged and selected [13] for research because it offers to economize and expedite the process of inquiry, [14] by being testable and by further factors in the economy of hypotheses: low cost, intrinsic value (instinctive naturalness and reasoned likelihood), and relations (caution, breadth, and incomplexity) among hypotheses, inquiries, etc. (as in the game of Twenty Questions). [15] The Century Dictionary Supplement definition of "working hypothesis" [2] reflects that perspective; Peirce may or may not have written it. [16] Peirce seldom used the phrase "working hypothesis," but he once commented about a related kind of a hypothesis that it was "a hypothesis, which like the working hypothesis of a scientific inquiry, we may not believe to be altogether true, but which is useful in enabling us to conceive of what takes place." [17] For Peirce the pragmatist, conceiving pragmatically of something meant conceiving of its effects in their conceivable implications as to informed practice in general including research. [18]

John Dewey used the concept of the working hypothesis as a pivotal feature in his theory of inquiry. [4] Contrary to the principles of verification and falsifiability, used in formal hypothesis testing found within dominant paradigms of 'normal' science, [19] working hypotheses were conceived by Dewey as neither true nor false but "provisional, working means of advancing investigation," which lead to the discovery of other unforeseen but "relevant" facts. [20] Dewey's development of the concept of the working hypothesis emerged from his contextualist epistemology in which absolute truth is unobtainable and replaced by "warranted assertability". [21] Thus, Dewey noted: [20]

The history of science also shows that when hypotheses have been taken to be finally true and hence unquestionable, they have obstructed inquiry and kept science committed to doctrines that later turned out to be invalid.

In Dewey's view, the working hypothesis is generated, not directly as a testable statement of, but instead in order to "direct inquiry into channels in which new material, factual and conceptual, is disclosed, material which is more relevant, more weighted and confirmed, more fruitful, than were the initial facts and conceptions which served as the point of departure". [20]

Abraham Kaplan later described the working hypothesis as "provisional or loosely formatted" theory or constructs. [22]

Design

Working hypotheses are constructed to facilitate inquiry; however, formal hypotheses can often be constructed based on the results of the inquiry, which in turn allows for the design of specific experiments whose data will either support or fail to support the formal hypotheses. In "Unity of Science as a Working Hypothesis" Oppenheim and Putnam (1958) argued that unitary science, in which laws from one branch could be equally useful by others, could only be accepted tentatively without further empirical testing. Thus they argued: [23]

We therefore think the assumption that unitary science can be attained through cumulative micro-reduction recommends itself as a working hypothesis. That is, we believe that it is in accord with the standards of reasonable scientific judgment to tentatively accept this hypothesis and to work on the assumption that further progress can be made in this direction.

In "The Working Hypothesis in Social Reform" George Herbert Mead (1899) takes a macro position and applies the notion of a working hypothesis to social reform. [24]

In the social world we must recognize the working hypothesis as the form into which all theories must be cast as completely as in the natural sciences. The highest criterion that we can present is that the hypothesis shall work in the complex of forces into which we introduce it" (p. 369).

Mead (1899) also expresses the tentative or provisional nature of working hypotheses.

Given its success (the working hypothesis), he (the social scientist) may restate his world from this standpoint and get the basis for further investigation that again always takes the form of a problem. The solution of this problem is found over again in the possibility of fitting his hypothetical proposition into the whole within which it arises. And he must recognize that this statement is only a working hypothesis at the best, i.e., he knows that further investigation will show that the former statement of his world is only provisionally true, and must be false from the standpoint of a larger knowledge, as every partial truth is necessarily false over against the fuller knowledge which he will gain later (p. 370).

For Putnam, the working hypothesis represents a practical starting point in the design of an empirical research exploration. A contrasting example of this conception of the working hypothesis is illustrated by the brain-in-a-vat thought experiment. This experiment involves confronting the global skeptic position that we, in fact, are all just brains in vats being stimulated by a mad scientist to believe that our reality is real. Putnam argued that this proposition, however, rests on a "magical theory of reference" in which the existential evidence necessary to validate it is assumed. [25] Thus, the brain-in-a-vat proposition does not make for much of a hypothesis at all since there is no means to verify its truth. It does, however, provide a contrast for what a good working hypothesis would look like: one suited to culling potential existential evidence of the subject at hand.

A more concrete example would be that of conjectures in mathematics – propositions which appear to be true but which are formally unproven. Very often, conjectures will be provisionally accepted as working hypotheses in order to investigate its consequences and formulate conditional proofs. [26]

Materials scientists Hosono et al. (1996) developed a working hypothesis about the nature of optically transparent and electrically conducting amorphous oxides. [27] This exploratory study evaluated the hypothesis's effectiveness using confirming examples (p. 169).

Application

In the field of public administration working hypotheses are used as a conceptual framework for exploratory, applied, empirical research. [28] [29] [30] Research projects that use working hypotheses use a deductive reasoning or logic of inquiry. [3] In other words, the problem and preliminary theory are developed ahead of time and tested using evidence. Working hypotheses (statements of expectation) are flexible and incorporate relational or non-relational statements. They are often used as ways to investigate a problem in a particular city or public agency. [31] [32] [33]

These projects are a type of case study and use multiple methods of evidence collection. [34] The working hypotheses are used as a device to direct evidence collection. As a result, working hypotheses are generally organized using sub-hypotheses, which specify in more detail the kinds of data or evidence needed to support the hypothesis. [3]

See also

Related Research Articles

<span class="mw-page-title-main">Charles Sanders Peirce</span> American thinker who founded pragmatism (1839–1914)

Charles Sanders Peirce was an American scientist, mathematician, logician, and philosopher who is sometimes known as "the father of pragmatism". According to philosopher Paul Weiss, Peirce was "the most original and versatile of America's philosophers and America's greatest logician". Bertrand Russell wrote "he was one of the most original minds of the later nineteenth century and certainly the greatest American thinker ever".

<span class="mw-page-title-main">Empiricism</span> Idea that knowledge comes only/mainly from sensory experience

In philosophy, empiricism is an epistemological view which holds that true knowledge or justification comes only or primarily from sensory experience and empirical evidence. It is one of several competing views within epistemology, along with rationalism and skepticism. Empiricists argue that empiricism is a more reliable method of finding the truth than purely using logical reasoning, because humans have cognitive biases and limitations which lead to errors of judgement. Empiricism emphasizes the central role of empirical evidence in the formation of ideas, rather than innate ideas or traditions. Empiricists may argue that traditions arise due to relations of previous sensory experiences.

<span class="mw-page-title-main">Scientific method</span> Interplay between observation, experiment, and theory in science

The scientific method is an empirical method for acquiring knowledge that has been referred to while doing science since at least the 17th century. The scientific method involves careful observation coupled with rigorous scepticism, because cognitive assumptions can distort the interpretation of the observation. Scientific inquiry includes creating a testable hypothesis through inductive reasoning, testing it through experiments and statistical analysis, and adjusting or discarding the hypothesis based on the results.

<span class="mw-page-title-main">Abductive reasoning</span> Inference seeking the simplest and most likely explanation

Abductive reasoning is a form of logical inference that seeks the simplest and most likely conclusion from a set of observations. It was formulated and advanced by American philosopher and logician Charles Sanders Peirce beginning in the latter half of the 19th century.

<span class="mw-page-title-main">Pragmatism</span> Philosophical tradition

Pragmatism is a philosophical tradition that views language and thought as tools for prediction, problem solving, and action, rather than describing, representing, or mirroring reality. Pragmatists contend that most philosophical topics—such as the nature of knowledge, language, concepts, meaning, belief, and science—are best viewed in terms of their practical uses and successes.

Scientific evidence is evidence that serves to either support or counter a scientific theory or hypothesis, although scientists also use evidence in other ways, such as when applying theories to practical problems. Such evidence is expected to be empirical evidence and interpretable in accordance with the scientific method. Standards for scientific evidence vary according to the field of inquiry, but the strength of scientific evidence is generally based on the results of statistical analysis and the strength of scientific controls.

<span class="mw-page-title-main">Pragmaticism</span>

"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 journals". Peirce in 1905 announced his coinage "pragmaticism", saying that it was "ugly enough to be safe from kidnappers". Today, outside of philosophy, "pragmatism" is often taken to refer to a compromise of aims or principles, even a ruthless search for mercenary advantage. Peirce gave other or more specific reasons for the distinction in a surviving draft letter that year and in later writings. Peirce's pragmatism, that is, pragmaticism, differed in Peirce's view from other pragmatisms by its commitments to the spirit of strict logic, the immutability of truth, the reality of infinity, and the difference between (1) actively willing to control thought, to doubt, to weigh reasons, and (2) willing not to exert the will, willing to believe. In his view his pragmatism is, strictly speaking, not itself a whole philosophy, but instead a general method for the clarification of ideas. He first publicly formulated his pragmatism as an aspect of scientific logic along with principles of statistics and modes of inference in his "Illustrations of the Logic of Science" series of articles in 1877-8.

<span class="mw-page-title-main">Hypothetico-deductive model</span> Proposed description of the scientific method

The hypothetico-deductive model or method is a proposed description of the scientific method. According to it, scientific inquiry proceeds by formulating a hypothesis in a form that can be falsifiable, using a test on observable data where the outcome is not yet known. A test outcome that could have and does run contrary to predictions of the hypothesis is taken as a falsification of the hypothesis. A test outcome that could have, but does not run contrary to the hypothesis corroborates the theory. It is then proposed to compare the explanatory value of competing hypotheses by testing how stringently they are corroborated by their predictions.

A conceptual framework is an analytical tool with several variations and contexts. It can be applied in different categories of work where an overall picture is needed. It is used to make conceptual distinctions and organize ideas. Strong conceptual frameworks capture something real and do this in a way that is easy to remember and apply.

A pragmatic theory of truth is a theory of truth within the philosophies of pragmatism and pragmaticism. Pragmatic theories of truth were first posited by Charles Sanders Peirce, William James, and John Dewey. The common features of these theories are a reliance on the pragmatic maxim as a means of clarifying the meanings of difficult concepts such as truth; and an emphasis on the fact that belief, certainty, knowledge, or truth is the result of an inquiry.

<span class="mw-page-title-main">Operationalization</span> Part of the process of research design

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 measurable, though its existence is inferred from other phenomena. Operationalization thus defines a fuzzy concept so as to make it clearly distinguishable, measurable, and understandable by empirical observation. In a broader sense, it defines the extension of a concept—describing what is and is not an instance of that concept. For example, in medicine, the phenomenon of health might be operationalized by one or more indicators like body mass index or tobacco smoking. As another example, in visual processing the presence of a certain object in the environment could be inferred by measuring specific features of the light it reflects. In these examples, the phenomena are difficult to directly observe and measure because they are general/abstract or they are latent. Operationalization helps infer the existence, and some elements of the extension, of the phenomena of interest by means of some observable and measurable effects they have.

<span class="mw-page-title-main">Thomas Chrowder Chamberlin</span> American geologist and educator (1843–1928)

Thomas Chrowder Chamberlin was an American geologist and educator. In 1893 he founded the Journal of Geology, of which he was editor for many years.

A "natural kind" is an intellectual grouping, or categorizing of things, in a manner that is reflective of the actual world and not just human interests. Some treat it as a classification identifying some structure of truth and reality that exists whether or not humans recognize it. Others treat it as intrinsically useful to the human mind, but not necessarily reflective of something more objective. Candidate examples of natural kinds are found in all the sciences, but the field of chemistry provides the paradigm example of elements.

Exploratory research is "the preliminary research to clarify the exact nature of the problem to be solved." It is used to ensure additional research is taken into consideration during an experiment as well as determining research priorities, collecting data and honing in on certain subjects which may be difficult to take note of without exploratory research. It can include techniques, such as:

Neopragmatism is a variant of pragmatism that infers that the meaning of words is a result of how they are used, rather than the objects they represent.

Descriptive research is used to describe characteristics of a population or phenomenon being studied. It does not answer questions about how/when/why the characteristics occurred. Rather it addresses the "what" question. The characteristics used to describe the situation or population are usually some kind of categorical scheme also known as descriptive categories. For example, the periodic table categorizes the elements. Scientists use knowledge about the nature of electrons, protons and neutrons to devise this categorical scheme. We now take for granted the periodic table, yet it took descriptive research to devise it. Descriptive research generally precedes explanatory research. For example, over time the periodic table's description of the elements allowed scientists to explain chemical reaction and make sound prediction when elements were combined.

<span class="mw-page-title-main">Inquiry</span> Any process that has the aim of augmenting knowledge, resolving doubt, or solving a problem

An inquiry is any process that has the aim of augmenting knowledge, resolving doubt, or solving a problem. A theory of inquiry is an account of the various types of inquiry and a treatment of the ways that each type of inquiry achieves its aim.

<span class="mw-page-title-main">Community of inquiry</span> Group of people involved in a process of empirical or conceptual inquiry into a situation

The community of inquiry (CoI) is a concept first introduced by early pragmatist philosophers C.S.Peirce and John Dewey, concerning the nature of knowledge formation and the process of scientific inquiry. The community of inquiry is broadly defined as any group of individuals involved in a process of empirical or conceptual inquiry into problematic situations. This concept was novel in its emphasis on the social quality and contingency of knowledge formation in the sciences, contrary to the Cartesian model of science, which assumes a fixed, unchanging reality that is objectively knowable by rational observers. The community of inquiry emphasizes that knowledge is necessarily embedded within a social context and, thus, requires intersubjective agreement among those involved in the process of inquiry for legitimacy.

<span class="mw-page-title-main">Hypothesis</span> Proposed explanation for an observation, phenomenon, or scientific problem

A hypothesis is a proposed explanation for a phenomenon. For a hypothesis to be a scientific hypothesis, the scientific method requires that one can test it. Scientists generally base scientific hypotheses on previous observations that cannot satisfactorily be explained with the available scientific theories. Even though the words "hypothesis" and "theory" are often used interchangeably, a scientific hypothesis is not the same as a scientific theory. A working hypothesis is a provisionally accepted hypothesis proposed for further research in a process beginning with an educated guess or thought.

<span class="mw-page-title-main">Patricia M. Shields</span> Political scientist

Patricia M. Shields is a Regents' Professor in the Political Science Department at Texas State University. Since 2001 she has been Editor-in-Chief of the international and interdisciplinary journal Armed Forces & Society. She is also a Contributing Editor to Parameters: The US Army War College Quarterly and the Section Editor of the Military and Society section to the Handbook of Military Sciences. Shields is notable for her publications focusing on research methods, civil military relations, gender issues, pragmatism in public administration, peace studies, and the contributions of Jane Addams to public administration and peace theory. She received a BA in Economics from the University of Maryland - College Park, an MA in Economics and a PhD in Public Administration from The Ohio State University.

References

  1. ↑ Oxford Dictionary of Sports Science & Medicine. Eprint via Answers.com.
  2. 1 2 See in "hypothesis", Century Dictionary Supplement, v. 1, 1909, New York: The Century Company. Reprinted, v. 11, p. 616 (via Internet Archive] of the Century Dictionary and Cyclopedia, 1911.
    hypothesis [...]—Working hypothesis, a hypothesis suggested or supported in some measure by features of observed facts, from which consequences may be deduced which can be tested by experiment and special observations, and which it is proposed to subject to an extended course of such investigation, with the hope that, even should the hypothesis thus be overthrown, such research may lead to a tenable theory.
  3. 1 2 3 4 Casula, Mattia; Rangarajan, Nandhini; Shields, Patricia M. (October 2021). "The potential of working hypotheses for deductive exploratory research". Quality & Quantity . 55 (5): 1703–1725. doi: 10.1007/s11135-020-01072-9 . PMC   7722257 . PMID   33311812.
  4. 1 2 Shields, Patricia and Rangarjan, N. (2013). A Playbook for Research Methods: Integrating Conceptual Frameworks and Project Management. Stillwater, OK: New Forums Press. See Chapter 5.
  5. ↑ Shields, Patricia M.; Tajalli, Hassan (2006). "Intermediate Theory: The Missing Link in Successful Student Scholarship". Journal of Public Affairs Education. 12 (3): 313–334. doi:10.1080/15236803.2006.12001438. hdl: 10877/3967 . S2CID   141201197.
  6. ↑ Shields, Patricia M. (1998). "Pragmatism As a Philosophy of Science: A Tool For Public Administration". In Jay D. White (ed.). Research in Public Administration. Vol. 4. Emerald Group Publishing Limited. pp. 195–225 [211]. hdl: 10877/3954 . ISBN   1-55938-888-9.
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  8. ↑ Peirce, C. S. (1908), "A Neglected Argument for the Reality of God", Hibbert Journal v. 7, pp. 90–112. See both part III and part IV. Reprinted, including originally unpublished portion, in Collected Papers v. 6, paragraphs 452–85, The Essential Peirce v. 2, pp. 434–50, and elsewhere.
  9. ↑ Chamberlin, Thomas C. (1890). "The method of multiple working hypotheses". Science. 15 (366): 92–96. doi:10.1126/science.ns-15.366.92. PMID   17782687. (see 1965 reprint for free fulltext)
  10. ↑ Chamberlin, Thomas C. (1897). "Studies for students: the method of multiple working hypotheses". Journal of Geology. 5 (8): 837–848. Bibcode:1897JG......5..837C. doi: 10.1086/607980 . JSTOR   30054868.
  11. ↑ Elliot, L.P.; B. W. Brook (2007). "Revisiting Chamberlin: multiple working hypotheses for the 21st century". BioScience. 57 (7): 608–614. doi:10.1641/B570708.
  12. ↑ Chamberlin, Thomas C. (1965). "The method of multiple working hypotheses". Science. 148 (3671): 754–759. Bibcode:1965Sci...148..754C. doi:10.1126/science.148.3671.754. JSTOR   1716334. PMID   17748786. S2CID   7481185. (free fulltext)
  13. ↑ Peirce, C. S., Carnegie Application (L75, 1902, New Elements of Mathematics v. 4, pp. 37–38. See under "Abduction" at the Commens Dictionary of Peirce's Terms:
    Methodeutic has a special interest in Abduction, or the inference which starts a scientific hypothesis. For it is not sufficient that a hypothesis should be a justifiable one. Any hypothesis which explains the facts is justified critically. But among justifiable hypotheses we have to select that one which is suitable for being tested , experiment.
  14. ↑ Peirce, C. S. (1902), application to the Carnegie Institution, see MS L75.329–330, from Draft D Archived 24 May 2011 at the Wayback Machine of Memoir 27:
    Consequently, to discover is simply to expedite an event that would occur sooner or later, if we had not troubled ourselves to make the discovery. Consequently, the art of discovery is purely a question of economics. The economics of research is, so far as logic is concerned, the leading doctrine with reference to the art of discovery. Consequently, the conduct of abduction, which is chiefly a question of heuretic and is the first question of heuretic, is to be governed by economical considerations.
  15. ↑ Peirce, C. S. (1901 MS), "On The Logic of Drawing History from Ancient Documents, Especially from Testimonies", manuscript corresponding to an abstract delivered at the National Academy of Sciences meeting of November 1901. Published in 1958 in Collected Papers v. 7, paragraphs 162–231; see 220. Reprinted (first half) in 1998 in The Essential Peirce v. 2, pp. 75–114; see 107–110.
  16. ↑ See Peirce Edition Project (UQÀM) – in short Archived 6 July 2011 at the Wayback Machine from the Peirce Edition Project's branch at Université du Québec à Montréal (UQÀM), which is working on Writings v. 7: Peirce's work on the Century Dictionary. Peirce worked on the Century during the years between 1883 and 1909. Find "hypothesis" in PEP-UQÀM's list of words in Peirce's charge under "H". "Pragmatism" was also in Peirce's charge (see under "P", but Joseph M. Ransdell reported that PEP-UQÀM's director François Latraverse informed him that John Dewey actually wrote it (see Ransdell's 2006 January 13 post to peirce-l).
  17. ↑ Peirce, C. S. Collected Papers v. 7, paragraph 534, from an undated manuscript.
  18. ↑ Peirce, C. S. (1878), "How to Make Our Ideas Clear", Popular Science Monthly, v. 12, 286–302. Reprinted widely, including The Essential Peirce v. 1, pp. 109–123.
  19. ↑ Kuhn, Thomas (1962). The Structure of Scientific Revolutions (2nd ed.). University of Chicago Press. p.  147.
  20. 1 2 3 Dewey, John (1938). Logic: The Theory of Inquiry. Henry Holt and Company. pp. 142–143. ISBN   0-03-005250-5.
  21. ↑ Rysiew, Patrick (7 September 2007). "Epistemic Contextualism". Stanford Encyclopedia of Philosophy . Retrieved 19 May 2011.
  22. ↑ Kaplan, Abraham (1964). The Conduct of Inquiry: Methodology for Behavioral Science . Scranton, PA: Chandler Publishing Company. p.  268. ISBN   0-7658-0448-4. OCLC   711107.
  23. ↑ Oppenheim, Paul; Putnam, Hilary (1958). "Unity of Science as a Working Hypothesis" (PDF). Minnesota Studies in the Philosophy of Science. 2: 3–36.
  24. ↑ Mead, G.H. (1899) The Working Hypothesis is Social Reform. American Journal of Sociology 5(3) pp. 167–171.
  25. ↑ Putnam, Hilary (1982). "Brains in a vat". Reason, Truth, and History. Cambridge University Press. pp. 1–21.
  26. ↑ Stewart, Ian (2003). "Mathematics: Conjuring with Conjectures". Nature . 423 (6936): 124–127. Bibcode:2003Natur.423..124S. doi: 10.1038/423124a . PMID   12736663. S2CID   43252272.
  27. ↑ Hosono, H., Kikuchi, N., Ueda, N. and Kqwazoe, H. (1996) Working hypothesis to explore novel wide band gap electrically conducting amorphous oxides and examples, Journal of Non-Crystalline Solids 198–200 pp. 165–169
  28. ↑ Baum, Kevin (2003). "Understanding the Line – Staff Relationship in Fire Service." in Handbook of Conflict Management. Edited by William Pammer and Jerri Killian. New York: Marcel Dekker.
  29. ↑ Shields, Patricia M., 1998. "Pragmatism as a Philosophy of Science: A Tool for Public Administration", Research in Public Administration. Vol. 4:195–225.
  30. ↑ Shields, Patricia M. 2003. "A Pragmatic Teaching Philosophy", Journal of Public Affairs Education. Vol. 9, No. 1: 7–12.
  31. ↑ Swift, James T. 2010. "Exploring Capital Metro's Sexual Harassment Training Using Dr. Bengt-Ake Lundvall's Taxonomy of Knowledge Principles". Applied Research Projects, Texas State University.
  32. ↑ Gillfillan, Abigail. 2008. "Using Geographic Information Systems to Develop and Analyze Land-Use Policies". Applied Research Projects, Texas State University.
  33. ↑ Thornton, Wayne (2000). "A Descriptive and Exploratory Study of the Ethics Program at Austin State Hospital: The Common Elements of the Program and Managers' Beliefs About the Purpose and Usefulness of the Program". Applied Research Projects, Texas State University.
  34. ↑ Yin, Robert (2007). Case Study Research: Design and Methods. 4th edition. Thousand Oaks, CA: Sage
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