How LFP works
The most well-known and widely used lexical richness measure based on word frequency lists is probably the Lexical Frequency Profile (LFP; Laufer and Nation, 1995). The LFP divides words in a text into four different frequency layers: the first and the second 1000 most frequent words; the words in the Academic Word List (AWL; Coxhead, 2000); and words not found in any of the previous three groups. The LFP shows the percentage of words in the text accounted for by each layer. For example, if a learner’s essay contains a total of 200 word families, consisting of 160 from the first 1000-word list, 20 from the second, 10 from the AWL, and 10 from the ‘other words’ category, the LFP would be 80%–10%–5%–5%. Laufer and Nation (1995) show that the LFP correlates well with other lexical measures, discriminates between learners of different proficiency levels, and is relatively stable across two pieces of writing by the same learner.
However, the four LFP figures are interrelated with one another and are not easy to deal with statistically. The authors recognise this point, and to address it, Laufer (1995) proposes Beyond 2000, which is a condensed profile of the LFP. A Beyond 2000 score is calculated from the percentage of word families in the text that are not within the first 2,000 word families. Thus, for the previous example, the Beyond 2000 value would be 10%. Laufer (1995) argues that Beyond 2000 is as reliable and valid as the LFP but that it also allows one to arrive at one figure only rather than several, which makes it easier to compare lexical richness with other variables (such as passive vocabulary size).
Analytic tools for LFP
LFP and Beyond 2000 utilize the Range programs developed by Paul Nation,
Alex Heatley, and Averil Coxhead at Victoria University of Willington;
it is available on Nation’s website
(http://www.victoria.ac.nz/lals/about/staff/paul-nation/ ). There are currently three versions of the Range programs; one with
a GSL/AWL list, one with a British National Corpus list of 14,000 word
families, and a BNC list with 25,000 word families.
- Coxhead, A. (2000). A new academic word list. TESOL Quarterly, 34 (2), 213-238.
- Laufer, B. (1995). Beyond 2000. A measure of productive lexicon in a second
language. In L. Eubank, L. Selinker, & M. Sharwood Smith (Eds.), The current state of interlanguage (Studies in Honor of William E. Rutherford) (pp. 265-272). Amsterdm and Philadelphia, PA: John Benjamins.
- Laufer, B., & Nation, P. (1995). Vocabulary Size and Use: Lexical Richness
in L2 Written Production. Applied Linguistics, 16 (3), 307-322.