| Acknowledgements | 第6-8页 |
| Abstract | 第8-10页 |
| 中文摘要 | 第11-16页 |
| Chapter One INTRODUCTION | 第16-22页 |
| 1.1 Research Background | 第16-17页 |
| 1.2 Significance of the Study | 第17-19页 |
| 1.2.1 Theoretical Significance | 第17-18页 |
| 1.2.2 Methodological Significance | 第18-19页 |
| 1.2.3 Practical Significance | 第19页 |
| 1.3 Purpose of the Study | 第19-20页 |
| 1.4 Outline of the Thesis | 第20-22页 |
| Chapter Two Literature Review | 第22-38页 |
| 2.1 Lexical Richness | 第22-23页 |
| 2.1.1 Lexical Richness | 第22页 |
| 2.1.2 Lexical Sophistication | 第22-23页 |
| 2.2 Measures of Lexical Richness | 第23-38页 |
| 2.2.1 Unit of Measure | 第23-24页 |
| 2.2.2 Measures of Lexical Richness in Early Years | 第24-27页 |
| 2.2.3 Recent Researches on Measures of Lexical Diversity and Lexical Sophistication | 第27-32页 |
| 2.2.3.1 Recent Researches on Measures of Lexical Diversity | 第27-28页 |
| 2.2.3.2 Recent Researches on Measures of Lexical Sophistication | 第28-32页 |
| 2.2.4 Validating Recent Measures of Lexical Diversity and Lexical Sophistication | 第32-36页 |
| 2.2.4.1 Reliability and validity | 第32-34页 |
| 2.2.4.2 Empirical studies of Recent Measures of Lexical Diversity and Lexical Sophistication | 第34-36页 |
| 2.2.5 Problems with the Recent Measures of Lexical Sophistication | 第36-38页 |
| Chapter Three METHODOLOGY | 第38-49页 |
| 3.1 Research Questions | 第38-39页 |
| 3.2 Research Design | 第39-40页 |
| 3.3 A Computer Program for Measuring Lexical Sophistication | 第40-43页 |
| 3.3.1 Calculation of the Three Measures | 第40-41页 |
| 3.3.2 Information Provided by the Program | 第41-43页 |
| 3.3.3 Word Lists Available for the Program | 第43页 |
| 3.4 Data Collection | 第43-47页 |
| 3.4.1 Data for Testing Reliability | 第43-44页 |
| 3.4.2 Data for Testing Stability | 第44页 |
| 3.4.3 Data for Testing Construct Validity | 第44-46页 |
| 3.4.4 Data for Testing Concurrent Validity | 第46-47页 |
| 3.5 Data Processing | 第47-48页 |
| 3.6 Data Analysis | 第48-49页 |
| Chapter Four RESULTS AND DISCUSSIONS | 第49-69页 |
| 4.1 Results | 第49-62页 |
| 4.1.1 Reliability of the Three Measures | 第49-51页 |
| 4.1.2 Stability of the Three Measures | 第51-53页 |
| 4.1.3 Construct Validity of the Three Measures | 第53-58页 |
| 4.1.4 Concurrent Validity of the Three Measures | 第58-62页 |
| 4.1.4.1 A Weak Correlation between Lexical Sophistication and Writing Quality | 第58页 |
| 4.1.4.2 A Significant Difference between the Groups of Learners with Different Writing Abilities | 第58-59页 |
| 4.1.4.3 A Moderate Correlation between Lexical Sophistication and Lexical Diversity | 第59-60页 |
| 4.1.4.4 No Significant Correlation between Lexical Sophistication and Language Proficiency | 第60-61页 |
| 4.1.4.5 A Significant Difference between Two Groups of Essays Designed for Different Course Levels | 第61-62页 |
| 4.2 Discussions | 第62-69页 |
| 4.2.1 Reliability of the Three Measures | 第62页 |
| 4.2.2 Stability of the Three Measures | 第62-63页 |
| 4.2.3 Construct Validity of the Three Measures | 第63-65页 |
| 4.2.4 Concurrent Validity of the Three Measures | 第65-68页 |
| 4.2.4.1 Lexical Sophistication and Writing Quality | 第65-66页 |
| 4.2.4.2 Lexical Sophistication and Lexical Diversity | 第66-67页 |
| 4.2.4.3 Lexical Sophistication and Language Proficiency | 第67页 |
| 4.2.4.4 Validity Demonstrated by Discriminating between Different Course Levels | 第67-68页 |
| 4.2.5 Summary | 第68-69页 |
| Chapter Five CONCLUSIONS AND IMPLICATIONS | 第69-75页 |
| 5.1 Major Findings | 第69-70页 |
| 5.2 Implications | 第70-73页 |
| 5.2.1 Theoretical Implications | 第70-71页 |
| 5.2.2 Methodological Implications | 第71-72页 |
| 5.2.3 Pedagogical Implications | 第72-73页 |
| 5.3 Limitations of the Present Study and Suggestions for Future Studies | 第73-75页 |
| References | 第75-81页 |
| Appendix | 第81-84页 |
