Chapter 6
Establishing a ‘new normal’
Detecting fluctuating trends in word frequency over time
In this chapter we introduce statistical methods and associated visualisations for the analysis of lexical
change on a monthly basis in a 1.8-billion word news corpus spanning over 30 years. In previous work (Kehoe et al. 2022) we found examples of word frequency change in a data-driven
manner by applying existing statistical tests. An ongoing limitation is that, as our diachronic corpus grows, so too
does the possibility of a word exhibiting multiple frequency changes in different directions. This chapter reframes
the problem as one of time-series segmentation, dividing the frequency history of a word into timespans exhibiting
consistent upward or downward change. We then determine reasons for such changes by applying horizon graph
visualisations to collocates.
Article outline
- 1.Introduction and background
- 1.1From corpus to time series
- 1.2Identifying changes in frequency
- 1.3Exploring collocational change
- 2.Method
- 2.1Visualising collocational change
- 3.Results and discussion
- 3.1Downward trends
- 3.2Upward trends
- 3.3Multiple abrupt shifts
- 3.4Multiple trends
- 4.Conclusion
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Notes
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References