| List of Tables | p. xi |
| List of Figures | p. xiii |
| Acknowledgements | p. xv |
| Measuring Lexical Diversity | |
| Introduction | p. 3 |
| Lexical diversity versus vocabulary richness | p. 3 |
| Overview of the content of this monograph | p. 4 |
| Lexical diversity | p. 5 |
| Research using lexical diversity as a variable | p. 6 |
| Analysis of historical documents | p. 7 |
| Studies of authors' style and dating works of literature | p. 7 |
| Forensic linguistics | p. 7 |
| Demographic influences on vocabulary use | p. 8 |
| Second language and bilingualism | p. 8 |
| Language assessment | p. 8 |
| Linguistic input and interaction | p. 10 |
| The 'noun bias' issue | p. 11 |
| Language impairment and delay | p. 11 |
| Specific language impairment | p. 12 |
| Intervention studies | p. 13 |
| Language in dementia | p. 13 |
| Aphasia | p. 13 |
| Schizophrenia | p. 14 |
| Conclusion | p. 14 |
| Traditional Approaches to Measuring Lexical Diversity | p. 16 |
| The number of different words (NDW) | p. 16 |
| The type-token ratio (TTR) | p. 19 |
| Mean segmental type-token ratio (MSTTR) | p. 25 |
| Other linguistic measures of range | p. 25 |
| Transformations of TTR | p. 26 |
| Conclusion | p. 29 |
| A Mathematical Model of Lexical Diversity | p. 31 |
| A seminal paper | p. 31 |
| The harmonic series hypothesis and further developments | p. 36 |
| Using population statistics | p. 40 |
| The most complete formulation | p. 41 |
| A mathematical model for diversity | p. 47 |
| Operationalising the model | p. 49 |
| A mathematical expression for ideal curves | p. 50 |
| Producing the graphs from real data | p. 51 |
| Standardising how the measurement is made | p. 54 |
| Making the measurement, D, and vocd | p. 55 |
| Summary | p. 57 |
| Validation of the Model and its Application to Language Corpora | |
| Early Child Language 1: the New England Corpus | p. 63 |
| Testing vocd | p. 63 |
| Investigating sensitivity to sample size | p. 64 |
| Method | p. 65 |
| Results | p. 66 |
| Reliability | p. 68 |
| Stability | p. 68 |
| Internal consistency | p. 68 |
| Morphemicisation | p. 69 |
| Criterion-related validity | p. 70 |
| Discussion | p. 71 |
| Conclusion | p. 73 |
| Early Child Language 2: the Bristol Corpus | p. 76 |
| The Bristol Corpus | p. 76 |
| Measures from the Bristol project | p. 78 |
| Method | p. 80 |
| The preparation of transcripts | p. 80 |
| The calculation of D | p. 81 |
| Results | p. 81 |
| The three versions of D | p. 81 |
| D (stem forms) | p. 84 |
| Criterion-related validity | p. 86 |
| Discussion | p. 89 |
| Conclusion | p. 93 |
| Lexical Diversity and the Investigation of Accommodation in Foreign Language Proficiency Interviews | p. 95 |
| Background: the oral interview | p. 95 |
| Method | p. 98 |
| The students | p. 99 |
| Student variables | p. 100 |
| Results | p. 102 |
| The students | p. 102 |
| The relationship between teacher D and student measures | p. 104 |
| Conclusion | p. 108 |
| A New Measure of Inflectional Diversity and its Application to English and Spanish Data Sets | p. 110 |
| Inflectional diversity in the New England Corpus | p. 111 |
| Inflectional diversity in the Bristol Corpus | p. 111 |
| The Spanish data | p. 113 |
| Conclusion | p. 116 |
| Different Word Categories and their Diversity: Type-Type versus Type-Token | |
| Comparing the Diversity of Lexical Categories: the Type-Type Ratio and Related Measures | p. 121 |
| Type-type ratios | p. 121 |
| Rare words | p. 123 |
| Diversity versus sophistication | p. 123 |
| Intrinsic versus extrinsic measurement of rarity | p. 125 |
| Extrinsic rarity measures in bilingual and second language research | p. 127 |
| Laufer and Nation's lexical frequency profile | p. 128 |
| Early child language and 'The home-school study of language and literacy development' of Dickinson, Snow and Tabors | p. 129 |
| The relationship between rarity measures and sample size | p. 131 |
| Vocabulary composition and early lexical style | p. 134 |
| The effect of sample size | p. 136 |
| The 'noun bias' issue | p. 138 |
| Nouns versus verbs: the effect of sample size | p. 142 |
| An empirical demonstration | p. 142 |
| A proposed solution to the sample size problem | p. 147 |
| Programming for limiting relative diversity (LRD) | p. 148 |
| LRD for Anne and her mother | p. 149 |
| Conclusion | p. 150 |
| Lexical Diversity and Lexical Sophistication in First Language Writing | p. 152 |
| Overview of the study | p. 153 |
| Method | p. 154 |
| The data | p. 154 |
| The quantitative text variables | p. 155 |
| Coding schemes and analytical procedures | p. 161 |
| Results | p. 162 |
| Trends in the text level variables | p. 162 |
| Inter-correlations | p. 170 |
| Regression analysis | p. 170 |
| Discussion | p. 171 |
| Differences by Key Stage and Level | p. 172 |
| Predicting National Curriculum Levels | p. 172 |
| Conclusion | |
| Overview and Conclusions | p. 179 |
| Flawed measures and confused results | p. 179 |
| A more robust measure | p. 180 |
| Interpreting the values of D | p. 181 |
| Cross-linguistic comparisons of lexical diversity | p. 183 |
| In conclusion | p. 184 |
| Notes | p. 185 |
| Glossary of technical terms and acronyms | p. 187 |
| References | p. 203 |
| Appendices | |
| Key to the CHAT Transcripts in Appendices II-IV | p. 221 |
| Extract from a Transcript in the Bristol Corpus | p. 222 |
| A French Transcript from the Reading Corpus | p. 224 |
| Extract from the Manchester Corpus Illustrating the %mor Tier | p. 226 |
| Documentation for vocd | p. 228 |
| Using vocd | p. 228 |
| Sample size | p. 228 |
| Preparation of files | p. 228 |
| The minimum command line | p. 229 |
| The output from vocd | p. 229 |
| Text-handling options | p. 230 |
| Combining options on the command line | p. 234 |
| Example of standard output from vocd using a transcript from the New England Corpus | p. 235 |
| Output from the limiting relative diversity (LRD) option in vocd using a file from Anne (anne03a.cha) in the Manchester Corpus | p. 238 |
| Index | p. 244 |
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