大学英语四级写作样卷的词汇复杂度分析

词汇复杂度是衡量外语学习者语言产出能力的重要指标，而大规模语言测试中的写作样卷与评分标准是阅卷员为考生评定写作成绩的主要依据。使用多种分析工具，从词汇变异度、词汇密度、词汇丰富度和错词数四个方面对2010年全国大学英语四级考试的写作样卷进行分析。结果发现：样卷反映的词汇范围窄，98.5%的用词在最常用的2 000词频范围内；所使用的词汇复杂度指标中，D值的解释力和区分敏感度最好；词汇密度、形符类符比、D值与专家对样卷的综合评分都呈现中度以上的显著相关性；不同水平文本在形符类符比、D值和词汇密度指标上存在显著差异；分数越低的学生在写作中犯拼写错误数越多，所犯拼写错误的严重程度越高。

Analyzing Lexical Richness in CET-4 Range Finder

In the discussion of lexical richness assessment in linguistic output in general and in assessing range finder in particular, the paper analyzes the CET-4 (2010) range finder in terms of lexical variation, lexical density, lexical sophistication and number of errors. The result shows that the lexical range is 98.5% within the most frequently used 2000 words; that the D value proves the most robust in interpretation and discrimination among different levels of writing achievement; that lexical density, TTR and D value are significantly correlated with the global scores of the range finder by testing experts; that lexical density, TTR and D value are significantly different among writings between high achievers and low achievers as well as the intermediate while there is no significant different between the intermediate and the low achievers; and that the lower level the testee is, the more lexical spelling error he or she makes.