corpus analysis (2) corpus linguistics richard xiao [email protected]
TRANSCRIPT
Outline of the session• Lecture
– Keyword– Reference corpus– Key keyword
• Practical– WST keyword– AntConc keyword– Wmatrix keyword / key concept– Extra: keyword analysis with CQPweb
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What is a keyword?• Keywords are those words whose frequency is
exceptionally high (positive keywords) or low (negative keywords) in comparison with a reference corpus– Keywords usually refer to positive keywords
– But negative keywords are equally interesting (see Xiao and McEnery 2005)
• They appear at the very end of your listing, in a different colour in WordSmith
• They are omitted automatically from a keywords database for key keyword analysis and a keyword plot
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Why keyword analysis?
• Indicating the ‘aboutness’ (Scott 1999) of a particular text or corpus– Contents analysis, discourse analysis
• Also revealing the salient features which are functionally related to a particular genre (Xiao and McEnery 2005)– Genre analysis, stylistic analysis
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How to do keyword analysis• Make a wordlist of the target corpus
• Locate or make a word list of a reference corpus– Scott (2005) “In search of a bad reference corpus”
• http://www.methodsnetwork.ac.uk/redist/pdf/es1_05scott.pdf
– The reference corpus is usually larger than the target corpus
– The appropriateness of a reference corpus depends on your research questions!
• Compare the frequency of each item in the two wordlists to extract keywords – done automatically
• Analyse and interpret keywords – you will do it!
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Keywords in the party speeches• Target corpus – just one text
– David Cameron's speech at the Conservative conference (10 October 2012, Manchester)
• http://www.bbc.co.uk/news/uk-politics-15189614 • Local copy available (David_speech Unicode text)
- download and unzip the file into a file folder:www.fass.lancs.ac.uk/projects/corpus/data/workshop3texts.zip
• Reference corpus– The 100-million-word BNC: download and unzip (local
copy available)www.lexically.net/downloads/version4/BNC_World.zip
• Tool– WST Keyword
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Wordlist of David’s speech
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Creating keyword list
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Keyword extraction in progress
Warning: It can take time if you have loaded two large wordlists
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Keywords in David’s speech
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Negative keyword
What do these keywords tell us?
Keyword: Plot view
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What companies do keywords keep?
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Why “marriage”?
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Key clusters
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Similar to word clusters, but only keywords are used.
Key keywords• A key keyword is one which is "key" in more than
one of a number of related texts– The more texts it is "key" in, the more "key key" it is– Can avoid extracting keywords which are unusually
frequent in only a small number of files
• Can be created automatically and as simple to extract as you do for keywords
• n.b. Negative keywords are omitted automatically from a key keyword list
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Making a batch wordlist
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Specify a folder where you can write
Batch making keyword lists
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Batch making keyword lists
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Specify a folder where you can write
Making a KW database
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Key keywords
key coverage of the corpus An "associate" is a keyword that appears in the same text
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Keyword in AntConc
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target corpus
reference corpus
Keyword in AntConc
Key words in David's speech (in relation to Ed's speech)
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Wmatrix: Keywords and key concepts
• POS and semantic tagging• Keyword / key concept analysis in Cameron’s
speech in comparison with Miliband’s speech• Copy and paste the speeches into two separate
text files– http://www.bbc.co.uk/news/uk-politics-15189614 – http://www.labour.org.uk/ed-milibands-speech-to-
labour-party-conference
• Save the two texts as David_speech.txt and Ed_speech.txtwww.fass.lancs.ac.uk/projects/corpus/data/workshop3texts.zip
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Wmatrix: Keywords and key concepts
• Login with your account using zhejiangxx account– http://ucrel.lancs.ac.uk/wmatrix3.html
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Tagging Wizard
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Tagging in progress
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Tagging result
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Labour frequency list
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KWIC concordance
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“My folders”
Upload and tag Ed’s speech
…and click on “My folders”
Warning: Your folder view may look different!30
Open David_speech folder and select Ed_speech in “Keyword compared to”
dropdown box
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Keyword list to download!
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Keyword cloud – even more interesting!
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David’s key concepts(“Key concepts compared to”)
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Keyword analysis in online corpora
• Using Lancaster’s CQPweb to compare British English (LOB+FLOB) and American English (Brown + Frown)
• Login CQPweb– http://cqpweb.lancs.ac.uk
• Similar analysis can be done at BSFU’s CQPweb corpus hub (different corpora) – http://124.193.83.252/cqp/
– Account: ID=pass=test
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Creating subcorpora
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Creating subcorpus BrE
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Creating subcorpus AmE
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Making wordlists
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Wordlist available now
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Computing keywords
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You can make adjustments to the statistical measure, cut-off point, and minimum frequency according your research purposes.
Keywords in BrE and AmE
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