Vocabulary richness, including lexical diversity and use of rare words, has an important role in assessing proficiency, diagnosing progress and testing theory in the study of language development. This book reviews different methods for quantifying how vocabulary is deployed in spontaneous speech and writing, before introducing an alternative approach which can assess overall lexical diversity, measure morphology development and compare the development of different word classes. The new approach is illustrated by its application to first and second language learners.

DAVID D. MALVERN is Professor of Education, University of Reading, UK. He has been Research Officer at the Royal Society, Visiting Professor Department of Educational Psychology, McGill University, and European Union and British Council Consultant. BRIAN J. RICHARDS is Professor of Education, University of Reading, UK, and for seventeen years was an associate editor of the Journal of Child Language NGONI CHIPERE is Lecturer in Language Arts, University of the West Indies in Barbados, and author of Understanding Complex Sentences: Native Speaker Variation in Syntactic Competence published by Palgrave in 2004. PILAR DURÁN gained a PhD at Boston University and was Research Officer, University of Reading, UK, before becoming Business Development Manager at Eurobios.

List of Tables List of Figures Acknowledgements PART I: MEASURING LEXICAL DIVERSITY Introduction Some Approaches to Measuring Lexical Diversity A Mathematical Model of Lexical Diversity PART II: VALIDATION OF THE MODEL THROUGH ITS APPLICATION TO LANGUAGE CORPORA Early Child Language 1: The New England Corpus Early Child Language 2: The Bristol Corpus Lexical Diversity and the Investigation of Accommodation in Foreign Language Proficiency Interviews A New Measure of Inflectional Diversity and its Application to English and Spanish Date Sets PART III: DIFFERENT WORD CATEGORIES AND THEIR DIVERSITY: TYPE-TYPE VERSUS TYPE-TOKEN Comparing the Diversity of Lexical Categories: The Type/Type Ratio and Related Measures Lexical Diversity and Lexical Sophistication in First Language Writing PART IV: CONCLUSION Overview and Conclusions Notes Glossary of Technical Terms and Acronyms Appendices Index