崔崢

Abstract：The breadth of vocabulary is of vital importance in measuring language learners vocabulary size.This article is to have a review on the definition and the measurement of the breadth of vocabulary knowledge.

Key words：breadth；of vocabulary knowledge；measurement

1.The definition of the breadth of vocabulary knowledge

The breadth of vocabulary knowledge belongs to the quantitative aspect of vocabulary knowledge and is concerned with the issue “how many words does a second language learner need”.As for the number of words the native speakers know，several studies have been conducted to test the vocabulary size and have given quite different results.Nation & Waring （1997）state that a university graduates will have a vocabulary of about 20，000 word families.Francis and Kucera （Nation and Waring，1997）note that with a vocabulary size of around 2000 a learner can know eighty percent of knowledge in a text.For foreign or second language learners，it is estimated that usually a vocabulary size of 2，000 to 3，000 words provides a good basis for language use.Researchers have put forward different word lists on the basis of frequency，such as the General Services List （West，1953）containing 2，000 head words which was once believed to be one of the best available lists.In China，many scholars have put their efforts to test second or foreign language learners vocabulary size and investigate ways to enlarge their vocabulary such as Gui Shichun，Deng Zhaochun etc.

The emphasis on vocabulary size boosts the teachers and students to enlarge their vocabulary size，which is beneficial to their language competence especially the reading comprehension proficiency.The researches provide good reference as well as scientific basis for teaching syllabus and vocabulary size tests.

2.Measurement of breadth of vocabulary knowledge

Vocabulary size can be measured receptively and productively.As regard to the receptive way，there are two approaches on testing vocabulary size---- dictionary-based approach and frequency-based approach.The dictionary-based approach is frequently used to test native speakers vocabulary size.Wesche and Paribakht （1996）pointed out that words could be chosen randomly from a dictionary to form a proportional sample.The second approach is a frequency-based one which is often adopted to test second language learners vocabulary （Read 2000）.It is based on the assumption that the more frequently a word appears in a given corpus，the more likely it is to be known by language users for whom the corpus is representative.

As to the productive way，a number of indices have been employed in written texts or transcribed oral texts to measure lexical variety or richness.Lexical Frequency Profile （LFP）is one of the representatives can be assessed by RANGE which is developed by Laufer and Nation （Nation 2001b）.The main strength of LFP is that it focuses directly on lexis，reveals a detailed picture of vocabulary use through several word frequency levels and thus can be regarded as a useful diagnostic tool as well as a research tool for lexical development.Laufer & Nation （1995）noted that it is a reliable and valid measure of lexical use in writing.To measure lexical growth in written or spoken production，a complementary index is type-token ratio （TTR）（Wesche & Paribakht，1996），which can also be called as Lexical Variation （LV）or Lexical Diversity （LD）.TTR is defined as the ratio in percent between the different word forms and the total word forms in the text.It shows how the learner is inclined to repeat the same words in his or her writing.The higher the TTR，the more varied the productive words are.

Bibliography：

[1] Read，J.& C.A.Chapelle，A Framework for Second Language Vocabulary Assessment [J].Language Testing，2001，（18）：1-32.

[2] Read，J.Measuring the Vocabulary Knowledge of Second Language Learners [J].RELC Journa，1988，（19）：12-25.

基金項目：河北省教育廳2018年河北省高等學校英語教學改革研究與實踐項目“SPOC混合模式下大學英語深度學習教學模式建構(gòu)”（課題批號：2018YYGJ054）

（作者單位：東北大學秦皇島分校）