Différance is a French term coined by Jacques Derrida. It is a central concept in Derrida's deconstruction, a critical outlook concerned with the relationship between text and meaning. The term différance means 'difference and deferral of meaning.'

1. Difference In Difference Pdf Converter
2. Difference In Difference Pdf 2017
3. Difference In Difference Pdf Download
4. Difference In Difference Model Ppt
5. Difference In Difference Pdf Download

The difference in difference (or 'double difference') estimator is defined as the difference in average outcome in the treatment group before and after treatment minus the difference in average outcome in the control group before and after treatment3: it is literally a 'difference of differences.' Get your eyes ready, these are pretty tricky. Grab a timer (or move at a leisurely pace) and see how many differences you can find between the two pictures in one minute. The first 10 slides display two pictures side by side. The one on the left is the original picture and the one of the right has been tweaked a little. Keep scrolling until the end to find the answer keys. Difference-in-Difference-in-Differences (DDD) If one is concerned that the estimated treatment effect might be spurious, a useful test involves finding a comparison group that should not be affected by the treatment. Suppose a state implements a health policy law that is aimed at improving the health of the elderly (age 65 and older).

• 2Between structure and genesis
• 3The web of language
• 4Deconstruction and the history of philosophy

Overview[edit]

Basic Difference-in-Differences Models in SAS®, continued 4 differences. Is the change in medication adherence in the non-VBID group between 2013 and 2014. Interaction measures the difference in slopes between the two groups: it is a direct measure of the difference -in differences between the two groups. It is a cross-platform application meaning the PDF file will look the same on a Windows as it will on a Mac and it also allows searching through PDF files. Adobe Acrobat, on the other hand, is a more advanced and paid version of the Reader but with additional features to create, print, and manipulate PDF files. DD attributes any differences in trends between the treatment and control groups, that occur at the same time as the intervention, to that intervention.

Derrida first uses the term différance in his 1963 paper 'Cogito et histoire de la folie'.^[1] The term différance then played a key role in Derrida's engagement with the philosophy of Edmund Husserl in Speech and Phenomena. The term was then elaborated in various other works, notably in his essay 'Différance' and in various interviews collected in Positions.^[2]

The ⟨a⟩ of différance is a deliberate misspelling of différence, though the two are pronounced identically, IPA: [difeʁɑ̃s] (différance plays on the fact that the French word différer means both 'to defer' and 'to differ'). This misspelling highlights the fact that its written form is not heard, and serves to further subvert the traditional privileging of speech over writing (see archi-writing and logocentrism), as well as the distinction between the sensible and the intelligible. The difference articulated by the ⟨a⟩ in différance is not apparent to the senses via sound, 'but neither cannot it belong to intelligibility, to the ideality which is not fortuitously associated with the objectivity of theorein or understanding.'^[3] This is because the language of understanding is already caught up in sensible metaphors—for example, θεωρεῖν (theōrein) means 'to see' in Ancient Greek.

In the essay 'Différance' Derrida indicates that différance gestures at a number of heterogeneous features that govern the production of textual meaning. The first (relating to deferral) is the notion that words and signs can never fully summon forth what they mean, but can only be defined through appeal to additional words, from which they differ. Thus, meaning is forever 'deferred' or postponed through an endless chain of signifiers. The second (relating to difference, sometimes referred to as espacement or 'spacing') concerns the force that differentiates elements from one another, and in so doing engenders binary oppositions and hierarchies that underpin meaning itself.

Derrida developed the concept of différance deeper in the course of an argument against the phenomenology of Husserl, who sought a rigorous analysis of the role of memory and perception in our understanding of sequential items such as music or language. Derrida's approach argues that because the perceiver's mental state is constantly in flux and differs from one re-reading to the next, a general theory describing this phenomenon is unachievable.

A term related to the idea of différance in Derrida's thought is the supplement, 'itself bound up in a supplementary play of meaning which defies semantic reduction.'^[4]

Between structure and genesis[edit]

Derrida approaches texts as constructed around elemental oppositions which all speech has to articulate if it intends to make any sense whatsoever. This is so because identity is viewed in non-essentialist terms as a construct, and because constructs only produce meaning through the interplay of differences inside a 'system of distinct signs'. This approach to text, in a broad sense,^[5][6] emerges from semiology advanced by Ferdinand de Saussure.

Saussure is considered one of the fathers of structuralism when he explained that terms get their meaning in reciprocal determination with other terms inside language:

In language there are only differences. Even more important: a difference generally implies positive terms between which the difference is set up; but in language there are only differences without positive terms. Whether we take the signified or the signifier, language has neither ideas nor sounds that existed before the linguistic system, but only conceptual and phonic differences that have issued from the system. The idea or phonic substance that a sign contains is of less importance than the other signs that surround it. ... A linguistic system is a series of differences of sound combined with a series of differences of ideas; but the pairing of a certain number of acoustical signs with as many cuts made from the mass thought engenders a system of values.^[7]

Saussure explicitly suggested linguistics was only a branch of a more general semiology, of a science of signs in general, being human codes only one among others. Nevertheless, in the end, as Derrida pointed out, he made of linguistics 'the regulatory model', and 'for essential, and essentially metaphysical, reasons had to privilege speech, and everything that links the sign to phone':^[8] Derrida will prefer to follow the more 'fruitful paths (formalization)' of a general semiotics without falling in what he considered 'a hierarchizing teleology' privileging linguistics, and speak of 'mark' rather than of language, not as something restricted to mankind, but as prelinguistic, as the pure possibility of language, working every where there is a relation to something else.

Derrida sees these differences as elemental oppositions working in all languages, systems of distinct signs, and codes, where terms don't have absolute meanings but instead draw meaning from reciprocal determination with other terms. This structural difference is the first component that Derrida will take into account when articulating the meaning of différance, a mark he felt the need to create and will become a fundamental tool in his lifelong work: deconstruction:^[9]

Différance is the systematic play of differences, of the traces of differences, of the spacing by means of which elements are related to each other. This spacing is the simultaneously active and passive (the a of différance indicates this indecision as concerns activity and passivity, that which cannot be governed by or distributed between the terms of this opposition) production of the intervals without which the 'full' terms would not signify, would not function.

But structural difference will not be considered without him already destabilizing from the start its static, synchronic, taxonomic, ahistoric motifs, remembering that all structure already refers to the generative movement in the play of differences:^[10]

The other main component of différance is deferring, which takes into account the fact that meaning is not only synchrony with all the other terms inside a structure, but also diachrony, with everything that was and will be said, in History, difference as structure and deferring as genesis:^[11][12]

'the a of différance also recalls that spacing is temporization, the detour and postponement by means of which intuition, perception, consummation—in a word, the relationship to the present, the reference to a present reality, to a being—are always deferred. Deferred by virtue of the very principle of difference which holds that an element functions and signifies, takes on or conveys meaning, only by referring to another past or future element in an economy of traces. This economic aspect of différance, which brings into play a certain not conscious calculation in a field of forces, is inseparable from the more narrowly semiotic aspect of différance.

This confirms the subject as not present to itself and constituted on becoming space, in temporizing and also, as Saussure said, that 'language [which consists only of differences] is not a function of the speaking subject':^[11]

It confirms that the subject, and first of all the conscious and speaking subject, depends upon the system of differences and the movement of différance, that the subject is not present, nor above all present to itself before différance, that the subject is constituted only in being divided from itself, in becoming space, in temporizing, in deferral; and it confirms that, as Saussure said, 'language [which consists only of differences] is not a function of the speaking subject.'

Questioned this myth of the presence of meaning in itself ('objective') and/or for itself ('subjective') Derrida will start a long deconstruction of all texts where conceptual oppositions are put to work in the actual construction of meaning and values based on the subordination of the movement of 'différance':^[11]

At the point at which the concept of différance, and the chain attached to it, intervenes, all the conceptual oppositions of metaphysics (signifier/signified; sensible/intelligible; writing/speech; passivity/activity; etc.)—to the extent that they ultimately refer to the presence of something present (for example, in the form of the identity of the subject who is present for all his operations, present beneath every accident or event, self-present in its 'living speech,' in its enunciations, in the present objects and acts of its language, etc.)- become non pertinent. They all amount, at one moment or another, to a subordination of the movement of différance in favor of the presence of a value or a meaning supposedly antecedent to différance, more original than it, exceeding and governing it in the last analysis. This is still the presence of what we called above the 'transcendental signified.'

But, as Derrida also points out, these relations with other terms express not only meaning but also values. The way elemental oppositions are put to work in all texts it is not only a theoretical operation but also a practical option.The first task of deconstruction, starting with philosophy and afterwards revealing it operating in literary texts, juridical texts, etc., would be to overturn these oppositions:^[13]

On the one hand, we must traverse a phase of overturning. To do justice to this necessity is to recognize that in a classical philosophical opposition we are not dealing with the peaceful coexistence of a vis-a-vis, but rather with a violent hierarchy. One of the two terms governs the other (axiologically, logically, etc.), or has the upper hand.

To deconstruct the opposition, first of all, is to overturn the hierarchy at a given moment. To overlook this phase of overturning is to forget the conflictual and subordinating structure of opposition.

It is not that the final task of deconstruction is to surpass all oppositions, because they are structurally necessary to produce sense. They simply cannot be suspended once and for all. But this does not obviate their need to be analyzed and criticized in all its manifestations, showing the way these oppositions, logical and axiological, are at work in all discourse for it to be able to produce meaning and values.^[14]

Illustration[edit]

For example, the word 'house' derives its meaning more as a function of how it differs from 'shed', 'mansion', 'hotel', 'building', etc. (Form of Content, which Louis Hjelmslev distinguished from Form of Expression) than how the word 'house' may be tied to a certain image of a traditional house (i.e. the relationship between signifier and signified) with each term being established in reciprocal determination with the other terms than by an ostensive description or definition.

When can we talk about a 'house' or a 'mansion' or a 'shed'? The same can be said about verbs, in all the world languages: when should we stop saying 'walk' and start saying 'run'? The same happens, of course, with adjectives: when must we stop saying 'yellow' and start saying 'orange', or stop defining as 'black' and start saying 'white', or 'rich' and 'poor', 'entrepreneur' and 'worker', 'civilized' and 'primitive', 'man' and 'animal', 'beast' and 'sovereign', 'christian' and 'pagan', or 'beautiful' and start saying 'ugly', or 'bad' and start saying 'good', or 'truth' and start saying 'false', 'determined' and 'free'? Or 'in' and 'out', 'here' and 'there', 'now' and 'then', 'past' and 'present' and 'future' and 'eternal'? Not only are the topological differences between the words relevant here, but the differentials between what is signified is also covered by différance. Deferral also comes into play, as the words that occur following 'house' or 'white' in any expression will revise the meaning of that word, sometimes dramatically so. This is true not only with syntagmatic succession in relation with paradigmatic simultaneity, but also, in a broader sense, between diachronic succession in History related with synchronic simultaneity inside a 'system of distinct signs'.

Thus, complete meaning is always 'differential' and postponed in language; there is never a moment when meaning is complete and total. A simple example would consist of looking up a given word in a dictionary, then proceeding to look up the words found in that word's definition, etc., also comparing with older dictionaries from different periods in time, and such a process would never end.

This is also true with all ontological oppositions and its many declensions, not only in philosophy as in human sciences in general, cultural studies, theory of Law, et cetera. For example: the intelligible and the sensible, the spontaneous and the receptive, autonomy and heteronomy, the empirical and the transcendental, immanent and transcendent, as the interior and exterior, or the founded and the founder, normal and abnormal, phonetic and writing, analysis and synthesis, the literal sense and figurative meaning in language, reason and madness in psychoanalysis, the masculine and feminine in gender theory, man and animal in ecology, the beast and the sovereign in the political field, theory and practice as distinct dominions of thought itself. In all speeches in fact (and by right) we can make clear how they were dramatized, how the cleavages were made during the centuries, each author giving it different centers and establishing different hierarchies between the terms in the opposition.

Paradox[edit]

It may seem contradictory to suggest that différance is neither a word nor a concept. The difference itself between words cannot only be another word. If that is the case then différance appeals to ontology, creating an even bigger problem. So différance is either an appeal to an infinite mystery (similar to God in theology) or becomes empty of any and all meaning and is thus rendered superfluous.

The web of language[edit]

We reside, according to this philosophy, in a web of language, or at least one of interpretation, that has been laid down by tradition and which shifts each time we hear or read an utterance—even if it is the same utterance. Différance and deconstruction are attempts to understand this web of language, to search, in Derrida's words, for the 'other of language'.^[15] This 'other of language' is close to what Anglophone Philosophy calls the Reference of a word. There is a deferment of meaning with each act of re-reading. There is a difference of readings with each re-reading. In Derrida's words, 'there is nothing outside the [con]text' of a word's use and its place in the lexicon. Text, in Derrida's parlance, refers to context and includes all about the 'real-life' situation of the speech/text (cf. speech act theory).

Temporal delay[edit]

For Derrida, the relationship between the Signifier and the Signified is not understood to be exactly like Saussure's. For Derrida, there was a deferral, a continual and indefinite postponement as the Signified can never be achieved. The formation of the linguistic sign is marked by movement, and is not static. The easiest way to understand this is to imagine Saussure's model as a two dimensional plane, where each signified is separated due to the difference in its sound image. (If two sound-images are exactly alike, one could not distinguish between the two.) Each signifier then would be a particular point. Derrida adds a third dimension, time. Now, the act of formation is accounted for. This is not to say that there is no relationship between the two. However, Derrida felt that the old model focused too heavily on the signifier, rather than on utterance and occurrence. The Signifier and the Signified are severed completely and irrevocably.

Example of word introduction[edit]

An example of this effect occurred in England during the Renaissance, when oranges began to be imported from the Mediterranean. Yellow and red came to be differentiated from a new colour term, 'orange'. What was the meaning of these words before 1600? – What is their meaning afterwards? Such effects go on often in the use of language and frequently this effect forms the basis of language/meaning. Such changes of meaning are also often centres of political violence, as is apparent in the differences invested in male/female, master/slave, citizen/foreigner etc. Derrida seeks to modulate and question these 'violent hierarchies' through deconstruction.

Perhaps it is a misconception that différance seeks contradictory meanings. It does not necessarily do so. It can, but what it usually describes is the re-experience, the re-arrival of the moment of reading. Roland Barthes remarked that 'those who fail to reread are obliged to read the same story everywhere'.^[16] This wry comment summarizes the phenomenon of different experience for each iteration.

We are discussing just one text—every text. No distinction is necessarily made between texts in this 'basic' level. The difference/deferral can be between one text and itself, or between two texts; this is the crucial distinction between traditional perspectives and deconstruction.

Deconstruction and the history of philosophy[edit]

Derrida's neographism (rather than neologism because 'neologism' would propose a logos, a metaphysical category; and (more simply) because, when uttered in French, 'différance' is indistinguishable from 'difference'—it is thus only a graphical modification, having nothing to do with a spoken logos) is, of course, not just an attempt at linguistics or to discuss written texts and how they are read. It is, most importantly, an attempt to escape the history of metaphysics; a history that has always prioritised certain concepts, e.g., those of substance, essence, soul, spirit (idealism), matter (realism), becoming, freedom, sense-experience, language, science etc. All such ideas imply self-presence and totality. Différance, instead, focuses on the play of presence and absence, and, in effecting a concentration of certain thinking, Derrida takes on board the thought of Freud's unconscious (the trace), Heidegger's destruction of ontotheology, Nietzsche's play of forces, and Bataille's notion of sacrifice in contrast to Hegel's Aufheben.

Différance is not only irreducible to any ontological or theological—ontotheological—reappropriation, but as the very opening of the space in which ontotheology—philosophy—produces its system and its history, it includes ontotheology, inscribing it and exceeding it without return.^[17]

Yet he does not approach this absence and loss with the nostalgia that marks Heidegger's attempt to uncover some original truths beneath the accretions of a false metaphysics that have accumulated since Socrates. Rather it is with the moods of play and affirmation that Derrida approaches the issue.

However, Derrida himself never claimed to have escaped from the metaphysics with what he has done. To the contrary, he criticises others for claiming to have demolished metaphysics thoroughly.

Negative theology[edit]

Derrida's non-concept of différance, resembles, but is not, negative theology, an attempt to present a tacit metaphysics without pointing to any existent essence as the first cause or transcendental signified. Following his presentation of his paper 'Différance' in 1968, Derrida was faced with an annoyed participant who said, 'It [différance] is the source of everything and one cannot know it: it is the God of negative theology.' Derrida's answer was, 'It is and it is not.'^[18]

In contrast to negative theology, which posits something supereminent and yet concealed and ineffable, différance is not quite transcendental, never quite 'real', as it is always and already deferred from being made present. As John Caputo writes, 'Différance is but a quasi-transcendental anteriority, not a supereminent, transcendental ulteriority.'^[19] The differences and deferrings of différance, Derrida points out, are not merely ideal, they are not inscribed in the contours of the brain nor do they fall from the sky, the closest approximation would be to consider them as historical, that is, if the word history itself did not mean what it does, the airbrushing speech of the victor/vanquished.

Derrida has shown an interest in negative or apophatic theology, one of his most important works on the topic being his essay 'Sauf le nom'.^[20]

Life and technics[edit]

In Of Grammatology, Derrida states that grammatology is not a 'science of man' because it is concerned with the question of 'the name of man.' This leads Derrida into a consideration of the work of André Leroi-Gourhan, and in particular his concepts of 'program,' 'exteriorisation,' and 'liberation of memory.' Derrida writes: 'Leroi-Gourhan no longer describes the unity of man and the human adventure thus by the simple possibility of the graphie in general; rather as a stage or an articulation in the history of life—of what I have called différance—as the history of the grammè.'^[21] Derrida thus explicitly refers the term différance to life, and in particular to life as the history of inscription and retention, whether this is genetic or technological (from writing to 'electronic card indexes'). And thus grammatology is not a science of man because it deconstructs any anthropocentrism, in the sense that the inscription in question falls on both sides of the divide human/non-human.

Yet, in the article 'Différance', Derrida refers différance not to physis, that is, life, but to 'all the others of physis—tekhnè, nomos, thesis, society, freedom, history, mind, etc.—as physis differed and deferred, or as physis differing and deferring.'^[22]Bernard Stiegler argues in his book, Technics and Time, 1, that this represents a hesitation in Derrida: 'Now phusis as life was already différance. There is an indecision, a passage remaining to be thought. At issue is the specificity of the temporality of life in which life is inscription in the nonliving, spacing, temporalisation, differentiation, and deferral by, of and in the nonliving, in the dead.'^[23] What this suggests to Stiegler is that grammatology—a logic of the grammè—must be supplemented with a history of grammatisation, a history of all the forms and techniques of inscription, from genetics to technics, each stage of which will be found to possess its own logic. Only in this way can différance be thought as the differing and deferral of life (life as the emergence of a difference from non-life, specifically as the deferral of entropy), and as the difference fromphysis through which the human must inevitably be defined (the human as the inauguration of another memory, neither the memory of genetics nor that of the individual, but rather a memory consisting in 'inscription in the nonliving,' that is, technical memory).

Notes[edit]

1. ^'The economy of this writing is a regulated relationship between that which exceeds and the exceeded totality: the différance of the absolute excess.' (Derrida, J., 1978. Cogito and the History of Madness. From Writing and Difference. Trans. A. Bass. London & New York: Routledge. p. 75.) Schultz and Fried in their vast bibliography of Derrida's work cite this sentence as where 'JD introduces différance' for the first time. (Schultz, W.R. & Fried, L.B., 1992. Jacques Derrida Bibliography. London & New York: Garland. p. 12.)
2. ^See Speech and Phenomena and other essays on Husserl's Theory of Signs, trans. David B. Allison (Evanston: Northwestern University Press, 1973), 'Différance'. Margins of Philosophy, trans. Alan Bass (Chicago & London: Chicago University Press, 1982) and Positions, trans. Alan Bass (Chicago, University of Chicago Press, 1971).
3. ^'Différance', Margins of Philosophy, p. 5.
4. ^Norris, Christopher (2002). Deconstruction : theory and practice (3. ed.). London: Routledge. p. 32. ISBN9780415280105.
5. ^Royle, Nicholas (2004) Jacques Derrida, pp. 62–63
6. ^Derrida and Ferraris (1997) p.76

   I take great interest in questions of language and rhetoric, and I think they deserve enormous consideration; but there is a point where the authority of final jurisdiction is neither rhetorical nor linguistic, nor even discursive. The notion of trace or of text is introduced to mark the limits of the linguistic turn. This is one more reason why I prefer to speak of 'mark' rather than of language. In the first place the mark is not anthropological; it is prelinguistic; it is the possibility of language, and it is every where there is a relation to another thing or relation to an other. For such relations, the mark has no need of language.

7. ^Saussure, Ferdinand de (1916 [trans. 1959]). Course in General Linguistics. New York: New York Philosophical Library. pp. 121–22.Check date values in: |year= (help)
8. ^Cf. Jacques Derrida, 'Interview with Julia Kristeva' in 'Positions' (The University of Chicago Press, 1981), pp. 21

   Although Saussure recognized the necessity of putting the phonic substance between brackets ('What is essential in language, we shall see, is foreign to the phonic character of the linguistic sign' [p. 21]. 'In its essence it [the linguistic signifier] is not at all phonic' [p. 164]), Saussure, for essential, and essentially metaphysical, reasons had to privilege speech, everything that links the sign to phone. He also speaks of the 'natural link' between thought and voice, meaning and sound (p. 46). He even speaks of 'thought-sound' (p. 156). I have attempted elsewhere to show what is traditional in such a gesture, and to what necessities it submits. In any event, it winds up contradicting the most interesting critical motive of the Course, making of linguistics the regulatory model, the 'pattern' for a general semiology of which it was to be, by all rights and theoretically, only a part. The theme of the arbitrary, thus, is turned away from its most fruitful paths (formalization) toward a hierarchizing teleology: 'Thus it can be said that entirely arbitrary signs realize better than any others the ideal of the semiological process; this is why language, the most complex and most widespread of the systems of expression, is also the most characteristic one of them all; in this sense linguistics can become the general pattern for all semiology, even though language is only a particular system' (p. 101). One finds exactly the same gesture and the same concepts in Hegel. The contradiction between these two moments of the Course is also marked by Saussure's recognizing elsewhere that 'it is not spoken language that is natural to man, but the faculty of constituting a language, that is, a system of distinct signs ... ,' that is, the possibility of the code and of articulation, independent of any substance, for example, phonic substance.

9. ^Cf. Jacques Derrida, 'Interview with Julia Kristeva' in 'Positions' (The University of Chicago Press, 1981), pp. 21
10. ^Cf. Jacques Derrida, 'Interview with Julia Kristeva' in 'Positions' (The University of Chicago Press, 1981), pp. 28–30

    It is also the becoming-space of the spoken chain—which has been called temporal or linear; a becoming-space which makes possible both writing and every correspondence between speech and writing, every passage from one to the other.

    The activity or productivity connoted by the a of différance refers to the generative movement in the play of differences. The latter are neither fallen from the sky nor inscribed once and for all in a closed system, a static structure that a synchronic and taxonomic operation could exhaust. Differences are the effects of transformations, and from this vantage the theme of différance is incompatible with the static, synchronic, taxonomic, ahistoric motifs in the concept of structure.

11. ^ ^abcCf. Jacques Derrida, 'Interview with Julia Kristeva' in 'Positions' (The University of Chicago Press, 1981), pp. 28–30
12. ^Burke, Patrick (1997). 'The Flesh as Urpräsentierbarkeit in the Interrogative: The Absence of a Question in Derrida'. In Dillon, M. C. (ed.). Ecart & Différance: Merleau-Ponty and Derrida on Seeing and Writing. Atlantic Highlands, NJ: Humanities Press International. p. 60. Derrida says that différance is removed from every possible mode of presence, like the unconscious of Freud, the force in Nietzsche, the Other in Levinas. So the question of différance must yield to the différance of the question and thus can never be asked, is forever absent.
13. ^Cf. Jacques Derrida, 'Interview with Jean-Louis Houdebine and Guy Scarpetta,' in 'Positions' (The University of Chicago Press, 1981), pp. 42–44
14. ^Cf. Jacques Derrida, 'Interview with Jean-Louis Houdebine and Guy Scarpetta,' in 'Positions' (The University of Chicago Press, 1981), p. 42

    When I say that this phase is necessary, the word phase is perhaps not the most rigorous one. It is not a question of a chronological phase, a given moment, or a page that one day simply will be turned, in order to go on to other things. The necessity of this phase is structural; it is the necessity of an interminable analysis: the hierarchy of dual oppositions always reestablishes itself. Unlike those authors whose death does not await their demise, the time for overturning is never a dead letter.

15. ^Richard Kearney, Dialogues with Contemporary Thinkers, Manchester: MUP, 1984
16. ^Barthes, Roland. S/Z. Trans. by Richard Miller. New York: Hill and Wang, 1974, pp. 15–6.
17. ^'Différance', Margins of Philosophy, p.6.
18. ^Caputo, John. The Prayers and Tears of Jacques Derrida. Bloomington: Indiana University Press, 1997, p. 2.
19. ^Caputo, Prayers and Tears, p. 3.
20. ^Derrida, Jacques. 'Sauf le nom'. On the Name. Stanford: Stanford University Press, 1995.
21. ^Derrida, Jacques. Of Grammatology, Baltimore & London: Johns Hopkins University Press, 1998, p. 84.
22. ^Derrida, Jacques. 'Différance', Margins of Philosophy, Chicago & London: University of Chicago Press, 1982, p. 17.
23. ^Stiegler, Bernard. Technics and Time, 1: The Fault of Epimetheus, Stanford: Stanford University Press, pp. 139–40.

References[edit]

• 'Speech and Phenomena' and other essays on Husserl's Theory of Signs, trans. David B. Allison (Evanston: Northwestern University Press, 1973).
• Of Grammatology (Baltimore: Johns Hopkins University Press, 1998, corrected edition).

External links[edit]

• Full text of Différance chapter, translated by Alan Bass, from Margins of Philosophy pp. 3–27 (Stanford University)

Difference in differences (DID^[1] or DD^[2]) is a statistical technique used in econometrics and quantitative research in the social sciences that attempts to mimic an experimental research design using observational study data, by studying the differential effect of a treatment on a 'treatment group' versus a 'control group' in a natural experiment.^[3] It calculates the effect of a treatment (i.e., an explanatory variable or an independent variable) on an outcome (i.e., a response variable or dependent variable) by comparing the average change over time in the outcome variable for the treatment group, compared to the average change over time for the control group. Although it is intended to mitigate the effects of extraneous factors and selection bias, depending on how the treatment group is chosen, this method may still be subject to certain biases (e.g., mean regression, reverse causality and omitted variable bias).

In contrast to a time-series estimate of the treatment effect on subjects (which analyzes differences over time) or a cross-section estimate of the treatment effect (which measures the difference between treatment and control groups), difference in differences uses panel data to measure the differences, between the treatment and control group, of the changes in the outcome variable that occur over time.

General definition[edit]

Difference in differences requires data measured from a treatment group and a control group at two or more different time periods, specifically at least one time period before 'treatment' and at least one time period after 'treatment.' In the example pictured, the outcome in the treatment group is represented by the line P and the outcome in the control group is represented by the line S. The outcome (dependent) variable in both groups is measured at time 1, before either group has received the treatment (i.e., the independent or explanatory variable), represented by the points P₁ and S₁. The treatment group then receives or experiences the treatment and both groups are again measured at time 2. Not all of the difference between the treatment and control groups at time 2 (that is, the difference between P₂ and S₂) can be explained as being an effect of the treatment, because the treatment group and control group did not start out at the same point at time 1. DID therefore calculates the 'normal' difference in the outcome variable between the two groups (the difference that would still exist if neither group experienced the treatment), represented by the dotted line Q. (Notice that the slope from P₁ to Q is the same as the slope from S₁ to S₂.) The treatment effect is the difference between the observed outcome and the 'normal' outcome (the difference between P₂ and Q).

Formal definition[edit]

Consider the model

${\displaystyle y_{it}={\gamma }_{s(i)}+{\lambda }_t+\delta I+{\epsilon }_{it}}$

where ${\displaystyle y_{it}}$ is the dependent variable for individual${\displaystyle i}$ and ${\displaystyle t}$, ${\displaystyle s(i)}$ is the group to which ${\displaystyle i}$ belongs (i.e. the treatment or the control group), and ${\displaystyle I(\dots )}$ is short-hand for the dummy variable equal to 1 when the event described in ${\displaystyle (\dots )}$ is true, and 0 otherwise. In the plot of time versus ${\displaystyle Y}$ by group, ${\displaystyle {\gamma }_s}$ is the vertical intercept for the graph for ${\displaystyle s}$, and ${\displaystyle {\lambda }_t}$ is the time trend shared by both groups according to the parallel trend assumption (see Assumptions below). ${\displaystyle \delta }$ is the treatment effect, and ${\displaystyle {\epsilon }_{it}}$ is the residual term.

Consider the average of the dependent variable and dummy indicators by group and time:

and suppose for simplicity that ${\displaystyle s=1,2}$ and ${\displaystyle t=1,2}$. Note that ${\displaystyle D_{st}}$ is not random; it just encodes how the groups and the periods are labeled. Then

The strict exogeneity assumption then implies that

${\displaystyle \mathrm{E}\left[({\overline{y}}_{11}-{\overline{y}}_{12})-({\overline{y}}_{21}-{\overline{y}}_{22})\right]=\delta (D_{11}-D_{12})+\delta (D_{22}-D_{21}).}$

Without loss of generality, assume that ${\displaystyle s=2}$ is the treatment group, and ${\displaystyle t=2}$ is the after period, then ${\displaystyle D_{22}=1}$ and ${\displaystyle D_{11}=D_{12}=D_{21}=0}$, giving the DID estimator

${\displaystyle \hat{\delta }=({\overline{y}}_{11}-{\overline{y}}_{12})-({\overline{y}}_{21}-{\overline{y}}_{22}),}$

which can be interpreted as the treatment effect of the treatment indicated by ${\displaystyle D_{st}}$. Below it is shown how this estimator can be read as a coefficient in an ordinary least squares regression. The model described in this section is over-parametrized; to remedy that, one of the coefficients for the dummy variables can be set to 0, for example, we may set ${\displaystyle {\gamma }_1=0}$.

Assumptions[edit]

Difference In Difference Pdf Converter

All the assumptions of the OLS model apply equally to DID. In addition, DID requires a parallel trend assumption. The parallel trend assumption says that ${\displaystyle {\lambda }_2-{\lambda }_1}$ are the same in both ${\displaystyle s=1}$ and ${\displaystyle s=2}$. Given that the formal definition above accurately represents reality, this assumption automatically holds. However, a model with ${\displaystyle {\lambda }_{st}:{\lambda }_{22}-{\lambda }_{21}\ne {\lambda }_{12}-{\lambda }_{11}}$ may well be more realistic.

As illustrated to the right, the treatment effect is the difference between the observed value of y and what the value of y would have been with parallel trends, had there been no treatment. The Achilles' heel of DID is when something other than the treatment changes in one group but not the other at the same time as the treatment, implying a violation of the parallel trend assumption.

To guarantee the accuracy of the DID estimate, the composition of individuals of the two groups is assumed to remain unchanged over time. When using a DID model, various issues that may compromise the results, such as autocorrelation and Ashenfelter dips, must be considered and dealt with.

Difference In Difference Pdf 2017

Implementation[edit]

The DID method can be implemented according to the table below, where the lower right cell is the DID estimator.

Running a regression analysis gives the same result. Consider the OLS model

${\displaystyle y={\beta }_0+{\beta }_{1}T+{\beta }_{2}S+{\beta }_3(T\cdot S)+\epsilon }$

where ${\displaystyle T}$ is a dummy variable for the period, equal to ${\displaystyle 1}$ when ${\displaystyle t=2}$, and ${\displaystyle S}$ is a dummy variable for group membership, equal to ${\displaystyle 1}$ when ${\displaystyle s=2}$. The composite variable ${\displaystyle (T\cdot S)}$ is a dummy variable indicating when ${\displaystyle S=T=1}$. Although it is not shown rigorously here, this is a proper parametrization of the model formal definition, furthermore, it turns out that the group and period averages in that section relate to the model parameter estimates as follows

where ${\displaystyle \hat{E}(\cdots \mid \dots )}$ stands for conditional averages computed on the sample, for example, ${\displaystyle T=1}$ is the indicator for the after period, ${\displaystyle S=0}$ is an indicator for the control group. To see the relation between this notation and the previous section, consider as above only one observation per time period for each group, then

and so on for other values of ${\displaystyle T}$ and ${\displaystyle S}$, which is equivalent to

${\displaystyle {\hat{\beta }}_3=(y_{11}-y_{21})-(y_{12}-y_{22}).}$

But this is the expression for the treatment effect that was given in the formal definition and in the above table.

Card and Krueger (1994) example[edit]

Consider one of the most famous DID studies, the Card and Krueger article on minimum wage in New Jersey, published in 1994.^[4] Card and Krueger compared employment in the fast food sector in New Jersey and in Pennsylvania, in February 1992 and in November 1992, after New Jersey's minimum wage rose from $4.25 to $5.05 in April 1992. Observing a change in employment in New Jersey only, before and after the treatment, would fail to control for omitted variables such as weather and macroeconomic conditions of the region. By including Pennsylvania as a control in a difference-in-differences model, any bias caused by variables common to New Jersey and Pennsylvania is implicitly controlled for, even when these variables are unobserved. Assuming that New Jersey and Pennsylvania have parallel trends over time, Pennsylvania's change in employment can be interpreted as the change New Jersey would have experienced, had they not increased the minimum wage, and vice versa. The evidence suggested that the increased minimum wage did not induce a decrease in employment in New Jersey, contrary to what simplistic economic theory would suggest. The table below shows Card & Krueger's estimates of the treatment effect on employment, measured as FTEs (or full-time equivalents). Card and Krueger estimate that the $0.80 minimum wage increase in New Jersey led to a 2.75 FTE increase in employment.

See also[edit]

References[edit]

Difference In Difference Pdf Download

1. ^Abadie, A. (2005). 'Semiparametric difference-in-differences estimators'. Review of Economic Studies. 72 (1): 1–19. CiteSeerX10.1.1.470.1475. doi:10.1111/0034-6527.00321.
2. ^Bertrand, M.; Duflo, E.; Mullainathan, S. (2004). 'How Much Should We Trust Differences-in-Differences Estimates?'(PDF). Quarterly Journal of Economics. 119 (1): 249–275. doi:10.1162/003355304772839588.
3. ^Angrist, J. D.; Pischke, J. S. (2008). Mostly Harmless Econometrics: An Empiricist's Companion. Princeton University Press. pp. 227–243. ISBN978-0-691-12034-8.
4. ^Card, David; Krueger, Alan B. (1994). 'Minimum Wages and Employment: A Case Study of the Fast-Food Industry in New Jersey and Pennsylvania'. American Economic Review. 84 (4): 772–793. JSTOR2118030.

Further reading[edit]

• Angrist, J. D.; Pischke, J. S. (2008). Mostly Harmless Econometrics: An Empiricist's Companion. Princeton University Press. pp. 227–243. ISBN978-0-691-12034-8.
• Imbens, Guido W.; Wooldridge, Jeffrey M. (2009). 'Recent Developments in the Econometrics of Program Evaluation'. Journal of Economic Literature. 47 (1): 5–86. doi:10.1257/jel.47.1.5.
• Bakija, Jon; Heim, Bradley (August 2008). 'How Does Charitable Giving Respond to Incentives and Income? Dynamic Panel Estimates Accounting for Predictable Changes in Taxation'. NBER Working Paper No. 14237. doi:10.3386/w14237.
• Conley, T.; Taber, C. (July 2005). 'Inference with 'Difference in Differences' with a Small Number of Policy Changes'. NBER Technical Working Paper No. 312. doi:10.3386/t0312.

Difference In Difference Model Ppt

External links[edit]

• Difference in Difference Estimation, Healthcare Economist website

Difference In Difference Pdf Download