Corpus analysis (2)

Corpus Linguistics

Richard Xiao

lancsxiaoz@googlemail.com

Outline of the session• Lecture

– Keyword– Reference corpus– Key keyword

• Practical– WST keyword– AntConc keyword– Wmatrix keyword / key concept– Extra: keyword analysis with CQPweb

2

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

3

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

4

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!

5

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

6

Wordlist of David’s speech

7

Creating keyword list

8

Keyword extraction in progress

Warning: It can take time if you have loaded two large wordlists

9

Keywords in David’s speech

10

Negative keyword

What do these keywords tell us?

Keyword: Plot view

11

What companies do keywords keep?

12

Why “marriage”?

13

Key clusters

14

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

15

Making a batch wordlist

16

Specify a folder where you can write

Batch making keyword lists

17

Batch making keyword lists

18

Specify a folder where you can write

Making a KW database

19

Key keywords

key coverage of the corpus An "associate" is a keyword that appears in the same text

20

Keyword in AntConc

21

target corpus

reference corpus

Keyword in AntConc

Key words in David's speech (in relation to Ed's speech)

22

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

23

Wmatrix: Keywords and key concepts

• Login with your account using zhejiangxx account– http://ucrel.lancs.ac.uk/wmatrix3.html

24

Tagging Wizard

25

Tagging in progress

26

Tagging result

27

Labour frequency list

28

KWIC concordance

29

“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

31

Keyword list to download!

32

Keyword cloud – even more interesting!

33

David’s key concepts(“Key concepts compared to”)

34

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

35

Creating subcorpora

36

Creating subcorpus BrE

37

Creating subcorpus AmE

38

Making wordlists

39

Wordlist available now

40

Computing keywords

41

You can make adjustments to the statistical measure, cut-off point, and minimum frequency according your research purposes.

Keywords in BrE and AmE

42