principles of corpus construction matthew brook odonnell university of liverpool - corpus...
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Principles of corpus construction
Matthew Brook O’Donnell
University of Liverpool - Corpus Linguistics Summer Institute 2008
Aims
What is a corpus? What principles guide the construction,
development and selection of a corpus? When and How to build a corpus Can the web be used for building corpora? Workshop: Build a small corpus of web texts
What is a corpus?
John Sinclair (1933-2007)
What is a corpus?
John Sinclair (1933-2007)
A corpus is a collection of pieces of language text in electronic form, selected according to external criteria to represent, as far as possible, a language or language variety as a source of data for linguistic research.
(Sinclair 2004)
What is a corpus?
John Sinclair (1933-2007)
A corpus is a collection of pieces of language text in electronic form, selected according to external criteria to represent, as far as possible, a language or language variety as a source of data for linguistic research.
(Sinclair 2004)
What is a corpus?
John Sinclair (1933-2007)
A corpus is a collection of pieces of language text in electronic form, selected according to external criteria to represent, as far as possible, a language or language variety as a source of data for linguistic research.
(Sinclair 2004)
What is a corpus?
John Sinclair (1933-2007)
A corpus is a collection of pieces of language text in electronic form, selected according to external criteria to represent, as far as possible, a language or language variety as a source of data for linguistic research.
(Sinclair 2004)
What is a corpus?
John Sinclair (1933-2007)
A corpus is a collection of pieces of language text in electronic form, selected according to external criteria to represent, as far as possible, a language or language variety as a source of data for linguistic research.
(Sinclair 2004)
What is a corpus?
John Sinclair (1933-2007)
A corpus is a collection of pieces of language text in electronic form, selected according to external criteria to represent, as far as possible, a language or language variety as a source of data for linguistic research.
(Sinclair 2004)
Corpus
Authentic language data Electronic/machine readable form Designed and collected according to
sampling procedures Representative of language For linguistic investigation
Corpus
Authentic language data Electronic/machine readable form Designed and collected according to
sampling procedures Representative of language For linguistic investigation
Corpus
Authentic language data Electronic/machine readable form Designed and collected according to
sampling procedures Representative of language For linguistic investigation
But first….
Let’s talk about food! How could we compile a representative list
(=CORPUS) of food/dishes from around the world?
How can we group these foods?
1. Where they come from
1. Continental Food Corpus
Europe
Asia
America (North & South)
?
How can we group these foods?
1. Where they come from
2. Their main component
2. Main component corpus
Fish
Meat
Vegetarian
Where do you eat it?
How can we group these foods?
1. Where they come from
2. Their main component
3. Where you usually eat it
3. ‘Fast food potential’ corpus
Takeaway
Restaurant
How can we group these foods?
1. Where they come from
2. Their main component
3. Where it is usually eaten
4. What you use to eat it
4. Consumption Implement Corpus
Knife& fork
Chopsticks
Hands
How can we group these foods?
1. Where they come from
2. Their main component
3. Where it is usually eaten
4. What you use to eat it
1+2. Continental & Main Component Corpus
Europe
Asia
America (North & South)
Fish Meat Veg.
Corpus
Authentic language data Electronic/machine readable form Designed and collected according to
sampling procedures Representative of language For linguistic investigation
Language corpora
Different types of corpus Corpus size Sample size Representativeness - sampling Classification criteria
Types of corpus
•Sample Corpus: a fixed sample of text, often used as a reference corpus for comparing
•Monitor Corpus: a corpus which develops and is added to or filtered depending on the researcher’s needs
•Mini-corpus: a small corpus (e.g. to be compared with a reference corpus)
•Multilingual Corpus: corpus in a variety of languages
Types of corpus
•Comparable Corpus: texts in 2 languages or 2 varieties but not matched up
•Parallel Corpus: texts are translations of each other, eg. Canadian Hansard, corpus of versions of Plato, Bible
•Translation Corpus: 2 or more sets of texts classified as either originals or translations, the purpose being to identify features of translation (Manchester: Baker)
•Diachronic Corpus: Helsinki, LOB v. FLOB
•Learner Corpus: texts are written by language learners
Corpus Size – Is bigger better?
1st Generation Corpora = 1 Million Words– BROWN, LOB– ICE corpora
2nd Generation Sample Corpora – BNC, ANC = 100 Million Words
Monitor Corpora– Bank of English (450+ million and growing!)
Specialized corpora– Depends on source and scope of problem under
investigation
Sample Size
‘Personally I would like to see ‘whole text’ as a default condition, thus classifying sample corpora as one of the categories of special corpora... To me the use of small samples is just a remnant of the early restraints on corpus building, and the advantages of whole texts can be set out in powerful argument. The use of samples of constant size gains only a spurious air of scientific method, since it confers no benefit on the corpus, and is as practical as Genghis Khan’s fabled policy of having all his soldiers the same height.’
(Sinclair 1995: 27-28)
Sampling
Population– Production– Reception
Classifying Texts
Internal Criteria– Topic (aboutness)– Register/Style
Classifying Texts
Internal Criteria– Topic (aboutness)– Register/Style
External Criteria (situational parameters)
Brits treat English with such disdain
By Mr M. Rasheed Iqbal
Published: June 30 2007 03:00 | Last updated: June 30 2007 03:00
From Mr M. Rasheed Iqbal.
Sir, I agree with Henry von Blumenthal (Letters, June 23). It is very discouraging to hear news presenters saying "gonna" and "wanna" on the BBC news.
We were brought up to speak English properly and it is disappointing to see Brits treat the language with such disdain.
I hope the BBC will stem the tide and pull up its socks.
M. Rasheed Iqbal,National Bank of Dubai,Deira, Dubai, UAE
Copyright The Financial Times Limited 2007
Mode
Primary Channel – Written
Format – Published (print & web)
Setting - Public
Tenor
Addressee– Plurality – individual (editor) / plural (readers)– Presence – absent– Interactiveness – written correspondence/response– Shared knowledge – readers of same publication
Addressor– Demographic: Male, from Dubai, works in Bank,
educated, at least bilingual?– Acknowledgement: Self-identified in text
Field
Factuality – responding to actual event (TV broadcast), expressing personal opinion
Purposes – complain, express viewpoint, condemn slipping standards, correct perceived decline
Topics – use of British English on BBC, value of language education in former era
When and How to build a corpus
1. DON’T! – use one of the available corporaa. If interested in differences in conversational language in
British English (age, sex, class etc. differences)… USE British National Corpus
b. Combine and subsample existing corpora to match your
2. Repurpose existing archive/collectiona. Any electronic texts available – results of surveys, DA/CA
transcripts
3. Build your own!a. OCR, download, extract from PDF
b. TYPE IT IN!!!!
Using the web as source for corpora
Web as corpus: Advantages
Massive (and expanding) amounts of electronic text
Whole texts Wide reach of text-types/topics/genres Much in the public domain Google (etc) as corpus query tool
Web as corpus: Disadvantages
So much text that balance is difficult to achieve
Copyright is difficult to ascertain for many documents
Pages containing large amounts of extraneous material (menus, formatting, graphics)
Explosion of information… who is writing it? Who is reading it?