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THE PERCENTAGE OF WORDS KNOWN IN A TEXT AND READING COMPREHENSION Norbert Schmitt University of Nottingham Xiangying Jia

THE PERCENTAGE OF WORDS KNOWN IN A TEXT AND READING COMPREHENSION Norbert Schmitt University of Nottingham Xiangying Jiang West Virginia University William Grabe Northern Arizona University. R eading Performance and Vocabulary Knowledge are Strongly Related. .50 - .75 (Laufer, 1992)

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THE PERCENTAGE OF WORDS KNOWN IN A TEXT AND READING COMPREHENSION Norbert Schmitt University of Nottingham Xiangying Jia

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  1. THE PERCENTAGE OF WORDS KNOWN IN A TEXT AND READING COMPREHENSION Norbert Schmitt University of Nottingham Xiangying Jiang West Virginia University William Grabe Northern Arizona University

  2. Reading Performance and Vocabulary Knowledge are Strongly Related .50 - .75 (Laufer, 1992) .78 - .82 (Qian, 1999) .73 - .77 (Qian, 2002)

  3. The Ability to Read Requires A Large Vocabulary How Much? Early Research 3,000 word families (Laufer, 1992) 5,000 individual words (Hirsh and Nation, 1992) 5,000 words Laufer (1989)

  4. The Ability to Read Requires A Large Vocabulary How Much? Recent Research 8,000-9,000 word families (Hu and Nation 2000; Nation, 2006) 1st 1,000 word families average about 6 members (types per family) 9th 1,000 frequency level average 3 members SO 8,000 word families = 34,660 individual word forms

  5. Why Different Estimates?3,000 vs 9,000 Word Families • Different criteria of ‘adequate’ comprehension (Laufer – 55%) • Short texts • Small participant numbers (66) • Old frequency counts (Dutch) • Determination of unknown words

  6. Vocabulary Coverage Laufer (1989) found 95% coverage was point which best distinguished ‘comprehenders’ vs. ‘noncomprehenders’ 95%  3,000 word families Hu and Nation (2000) tested comprehension at various coverages • 80% = No learners had adequate comprehension • 90% = Only a few • 95% = 35-41% At 95% coverage, less than half of the students were successful, so required coverage is higher: 98-99% 98-99%  8,000-9,000 word families

  7. Vocabulary Coverage So the vocabulary coverage requirement is critical: 3,000 vs 9,000 word families This study will directly explore the relationship between vocabulary coverage and reading comprehension

  8. Vocabulary Coverage / Reading Comprehension

  9. Vocabulary Coverage / Reading Comprehension

  10. Vocabulary Coverage / Reading Comprehension

  11. Features of Our Study • Longer texts (582 and 757 words) • Extensive vocabulary test • Extensive reading comprehension tests • Controlled for background knowledge of texts • 664 participants from different L1s

  12. Selection of Reading Passages

  13. Development of the Vocabulary Test • a checklist format (check the words they know) • 120 target words sampled from the texts and 30 nonwords • deleted anybody with over 3 nonwords checked (≥2 nonwords same result) • high sampling rate for a good estimate of how much vocabulary each learner knew in each text

  14. Development of the Reading Comprehension Tests • A two-part reading test for each passage • 14 multiple-choice items • 16 graphic organizer completion items • graphic organizers were created to reflect the major discourse structures of the text • fill in partially-completed graphic organizers

  15. Participants

  16. Procedure • 100 minutes for the entire test battery • Biodata survey (5 mins.) • Vocabulary checklist (15 mins.) • Reading the Climate passage and answer comprehension items (40 mins.) • Reading the Mice passage and answer comprehension items (40 mins.)

  17. Initial Screening • Eliminated participants who checked more than 3 nonwords • Eliminated participants who attempted less than 5 items in the graphic organizer task for either passage

  18. Scoring • Vocabulary percentage • automatically calculated by entering checklist selections into an EXCEL spreadsheet • Multiple-choice reading comprehension test • 1 point for each correct answer, 0 for incorrect ones • Graphic organizer reading comprehension test • 1 point for each acceptable answer and 0 for unacceptable ones • Interrater reliability .99

  19. Reliability Estimates of the Reading Test • .82 for the entire reading test • .79 for the Climate reading test • .65 for the Mice reading test • .59 for the multiple-choice items • .81 for the graphic organizer items • Note: based on KR-21, possible underestimation

  20. Vocabulary Coverage vs Reading Comprehension

  21. The Influence of Background Knowledge

  22. Graphic Organizer vs Multiple-Choice Tests

  23. Conclusions • The vocabulary coverage / comprehension relationship is essentially linear between 90% - 100% coverage • So coverage requirements depends on comprehension goals • 98% coverage is probably necessary, as 70% comprehension is desirable • But even 90% coverage leads to 50% comprehension • 100% coverage only lead to 75% comprehension, so successful reading requires more than vocabulary, but high vocabulary levels are clearly a key requirement • Higher background knowledge lead to about 10 percentage-points better comprehension • There is a large amount of variation among learners

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