Corpora in lexical studies

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Corpora in lexical studies

• Corpus Linguistics
• Richard Xiao
• lancsxiaoz_at_googlemail.com

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Aims of this session

• Lecture
• Corpus-based lexicography
• Collocation and colligation
• Lab session
• Collocation using WST
• Collocation using AntConc
• Collocation and colligation in Xaira
• Using the BNCweb to study collocation

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Corpus revolution in lexicographic and lexical
studies

• Lexicographic and lexical studies are the
  greatest beneficiaries of corpora
• Corpora have revolutionised dictionary making
  and reference publishing
• It is now nearly unheard of for new dictionaries
  and new editions of old dictionaries published
  from the 1990s onwards not to claim to be based
  on corpus data

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Why use corpora in dictionary making?

• Machine-readable corpora allow dictionary makers
  to extract all authentic, typical examples of the
  usage of a lexical item from a large body of text
  in a few seconds
• Corpora allow dictionary makers to select entries
  based on frequency information
• Corpora can readily provide frequency information
  and collocation information for readers
• Textual (e.g. register, genre and domain) and
  sociolinguistic (e.g. user gender and age)
  information encoded in corpora allows
  lexicographers to give a more accurate
  description of the usage of a lexical item

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Why use corpora in dictionary making?

• Corpus annotations such as part-of-speech tagging
  and word sense disambiguation also enable a more
  sensible grouping of words which are polysemous
  and homographs
• A monitor corpus allows lexicographers to track
  subtle change in the meaning and usage of a
  lexical item so as to keep their dictionaries
  up-to-date
• Corpus evidence can complement or refute the
  intuitions of individual lexicographers, which
  are not always reliable because of potential
  biases in intuitions

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Five emphases

• Changes brought about by corpora to dictionaries
  and other reference books - five emphases
  (Hunston 2002)
• an emphasis on frequency
• an emphasis on collocation and phraseology
• an emphasis on variation
• an emphasis on lexis in grammar
• an emphasis on authenticity

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Top 1000 written / spoken words
Authentic examples
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Corpus-based learner dictionaries

• First fully corpus-based dictionary
• Collins Cobuild English Dictionary (1987)
• Some corpus-based learner dictionaries
• Longman Dictionary of Contemporary English (3rd
  edition)
• Oxford Advanced Learners Dictionary (OALD, 5th
  edition)
• Cambridge International Dictionary of English
  (1st edition)

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Frequency dictionaries
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Collocation

• Collocation is among the linguistic concepts
  which have benefited most from advances in corpus
  linguistics
• What is collocation?
• strong tea, powerful car (Halliday 1976)
• collocations of a given word are statements of
  the habitual or customary places of that wordthe
  company that words keep (Firth 1968181-2)
• One of the meanings of night is its
  collocability with dark (Firth 1957196)
• a frequent co-occurrence of two lexical items in
  the language (Greenbaum 197482)
• expel a school child vs. cashier an army officer
• I propose to bring forward as a technical term,
  meaning by collocation, and apply the test of
  collocability (Firth 1957 194)

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Meaning by collocation

• There is frequently so high a degree of
  interdependence between lexemes which tend to
  occur in texts in collocation with one another
  that their potentiality for collocation is
  reasonably described as being part of their
  meaning (Lyons 1977 613)
• Complete description of the meaning of a word
  would have to include the other word or words
  that collocate with it
• You shall know a word by the company it keeps!
  (Firth 1968179)
• Collocation is part of the word meaning

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Two types of collocation

• Coherence collocation vs. neighbourhood
  (horizontal) collocation (Scott 1998)
• Coherence collocation
• Collocates associated with a word (e.g. letter
  stamp, post office)
• Neighbourhood collocation
• Words which do actually co-occur with the word
  (letter - my, this, a, etc)

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Coherence collocation

• A cover term for the cohesion that results from
  the co-occurrence of lexical items that are in
  some way or other typically associated with one
  another, because they tend to occur in similar
  environments. (Halliday Hasan 1976287)
• candle flame flicker
• hair comb curl wave
• sky sunshine cloud rain
• Difficult to measure using a statistical formula

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Neighbourhood collocation

• Collocation in corpus linguistics
• Structure of collocation collocation window
• We may use the term node to refer to an item
  whose collocations we are studying, and we may
  then define a span as the number of lexical items
  on each side of a node that we consider relevant
  to that node. Items in the environment set by the
  span we will call collocates. (Sinclair
  1966415)
• Casual vs. significant collocation
• Significant collocation collocation that occurs
  more frequently than would be expected (in a
  statistical sense) on the basis of the individual
  items
• n.b. Neighbourhood (horizontal) collocations can
  include some coherence collocations

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Intuition vs. collocation

• Greenbaum (1974) people disagree on
  collocations in introspection-based elicitation
  experiments
• Although collocation can be observed informally
  on the basis of intuitions, it is more reliable
  to measure it statistically, and for this a
  corpus is essential (Hunston 2002 68)
• Intuition is often a poor guide to collocation
• because each of us has only a partial knowledge
  of the language, we have prejudices and
  preferences, our memory is weak, our imagination
  is powerful (so we can conceive of possible
  contexts for the most implausible utterances),
  and we tend to notice unusual words or structures
  but often overlook ordinary ones (Krishnamurthy
  2000 32-33)
• Collocation can be measured on the basis of
  co-occurrence statistics (MI, z, t, LL etc)
  more discussion to follow

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Collocation is syntagmatic
Langue (Language system) paradigmatic

• famous boots. On the stroke of full time the
  
• Stoke the lead on the stroke of half-time
  with a goal
• Smith sin-binned on the stroke of half-time,
  added a
• clinched their win on the stroke of lunch after
  resuming
• chase by declaring on the stroke of lunch. ltpgt
  With a lead
• expectant crowd, on the stroke of midday. The
  bird
• hour began not upon the stroke of midnight but
  upon the
• of midnight but upon the stroke of noon. There
  was,
• booked in advance. On the stroke of seven, a
  gong summons
• Promptly on the stroke of six 'clock,
  the chooks
• from Edinburgh on the stroke of the
  Millennium.
• Parole (Utterance)
  syntagmatic

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Collocation vs. colligation

• Collocation
• Relationship between a lexical item and other
  lexical items
• Relationship between words at the lexical level
• E.g. very collocates with good
• Colligation
• Relationship between a lexical item and a
  grammatical category
• Relationship between words at the grammatical
  level
• E.g. very colligates with ADJ

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WST Collocate settings
Concord tab
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WST collocates
Strength of relationship is displayed as 0.000 if
it hasn't yet been computed
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Strength of collocation relationship
A wordlist is required
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Highlight and double click
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to see the selected collocate
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Collocates in AntConc
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Collocation in Xaira
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Colligation in Xaira
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Exploring collocation with BNCweb

• http//bncweb.lancs.ac.uk/bncwebSignup/user/login.
  php

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Search for sweet
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Concordances of sweet
KWIC view
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KWIC view
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Dropdown menu collocations
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Collocation setting
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Collocation database (default settings)
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Adjusting settings
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Noun collocates of sweet
Click on a word to see its collocation info
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Collocation info of sweet smell
Click on a number to see concordances of
collocates at that position
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Concordances of smell at R2
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Collocation statistics
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Rank by frequency
Frequent words crowd into the top of the
collocate list Are they genuine collocates?
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Rank by the t test

• Also focusing on frequent words?

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Rank by MI

• Infrequent words at the top of the list
• How useful are they (especially to English
  learners)?

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Rank by the z score

• Like MI, the z score also over-estimates
  infrequent items (e.g. nothings, afton, marjoram)

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Log-likelihood test
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Rank by MI3
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Rank by dice coefficient