How Large a Vocabulary Is Needed For Reading and Listening?

Author: I.S.P. Nation · Type: academic · Status: draft · URL: https://www.lextutor.ca/cover/papers/nation_2006.pdf

Licence: Canadian Modern Language Review 63(1), 59-82, 2006; publicly mirrored author PDF; short quotes citable with attribution

Summary

Paul Nation’s landmark coverage study using fourteen 1,000-word-family lists from the British National Corpus. If 98% lexical coverage is required for unassisted comprehension, learners need roughly 8,000-9,000 word families for written text and 6,000-7,000 for spoken text. The paper also recounts Hu and Nation (2000): at 80% coverage nobody achieved adequate comprehension, and a regression put the adequate-comprehension threshold at 98% (one unknown word in 50). These numbers define the vocabulary problem any reading product must solve, and they frame Immersive’s intercomprehension edge: for Romance-L1 readers, cognate transparency massively raises effective coverage from day one.

Insights

• Unassisted reading of authentic text requires roughly 8,000-9,000 word families (98% coverage); listening requires 6,000-7,000, which is why cold-start reading in an unrelated L2 takes years. (high, draft) vocabulary coverage threshold reading

  If 98% coverage of a text is needed for unassisted comprehension, then a 8,000 to 9,000 word-family vocabulary is needed for comprehension of written text and a vocabulary of 6,000 to 7,000 for spoken text. — Abstract

• The widely cited 98% coverage threshold (one unknown word in 50) comes from Hu and Nation’s regression on comprehension outcomes. (high, draft) vocabulary coverage threshold reading

  It was calculated that 98% text coverage (1 unknown word in 50) would be needed for most learners to gain adequate comprehension. — Text coverage and comprehension, p. 61

• At 80% known-word coverage (one unknown word in five) no learner achieved adequate comprehension, so comprehension aids or cognate transparency are essential when learners read early. (high, draft) vocabulary coverage threshold intercomprehension

  With a text coverage of 80% (that is, 20 out of every 100 words [1 in 5] were nonsense words), no one gained adequate comprehension. — Text coverage and comprehension, p. 61