An Exploratory Study On Lexical Richness Of Reading Comprehension Materials In National Matriculation English Tests

National Matriculation English Test (NMET), as one of the most influential national language tests, has always been a favored topic for educational and testing specialists. With the prosperous development of the newly issued English curriculum reform, researches on NMET have stepped into a new stage, too. The attractive move of the newly-issued English Curriculum Standards is the higher requirement of vocabulary for senior high school students.In the field of language testing, the faith is that a good test requires an appropriate balance among six qualities:reliability, validity, authenticity, inter-activeness, impact and practicality. Therefore, validity and reliability are the two fundamental factors among them. How to maintain high validity and reliability is the pursued goal shared by the researchers. In the pace of validity development, it changes into validity evidence. It is a unitary concept, which covers the validity and reliability to a large extent. The previous researches on validity of NMET are generally based on the traditional definitions and classifications of validity, which are overlapping and confusing. In order to standardize the validity research, unified standards should be employed. Standards for Educational and Psychological Testing published by American Educational Research Association, etc. in1999is acknowledged as the universal professional standards in applied linguistics. This thesis is supposed to supply the international standards, validity evidence, to guide the domestic teaching and testing to improve the quality of validity research. In the hope of making a further step to evaluate the NMET on the basis of a great amount of theoretical and empirical researches, this exploratory study on the validity evidence study of NMET reading comprehension materials involves data analysis comes into being.The main purpose of this research is to explore the validity evidence of NMET reading comprehension test from2007to2011in Guangdong province under the New English curriculum standards and National papers to testify the quality of the reading comprehension materials from different indexes of lexical richness to give suggestions to other areas. This goal will be put forth to by answering the following four specific questions:1) What about the indexes of words off-list in Guangdong papers and National papers?2) What about the indexes of lexical density between Guangdong and National papers?3) What about the indexes of lexical sophistication between Guangdong and National papers?4) What about the indexes of lexical variation between Guangdong and National papers?This study adopts statistical analysis by Range, a vocabulary computer-aided software proposed by Nation to analyze the vocabulary size and use. It presents the figure interpretation by tables clearly and briefly to answer the four research questions.Based on this research, conclusions are drawn out. Firstly, for the indexes of off-list words, the fluctuation in Guangdong is smaller than national ones. It becomes more stable in the following years than National Ⅰ and Ⅱ. And many off-list percentages of National Ⅰ are higher than Guangdong province, while less stable than Guangdong. Secondly, as for the lexical density indexes, Guangdong NMET keeps the proportion more stable than national ones. Thirdly, as for the indexes of lexical sophistication, Guangdong NMET keeps the indexes more stable while lower than National Ⅰ and Ⅱ. The writer can say Guangdong NMET is easier than National ones to some extent. Finally, for the indexes of lexical variation, National Ⅱ is the highest one, which implies that it has more varied vocabulary used. Therefore, readers can see that Guangdong’s is the lowest among the three papers from2007to2011, which the writer can get a conclusion that the vocabulary used in Guangdong province is less varied than others, although the changes of the three NMET versions’curves are all plain. In a word, the reading comprehension materials in Guangdong from2007-2011remain more stable than National ones after its reform, which has instructional aspects for other areas.Although there are some limitations, like sampling and data interpretation, the achievement is that the study has applied international professional testing standards to domestic validity research with certain depth and breadth. It has provided some inspiration of validity evidence and NMET design for future researchers, test developers and teachers to better understand and improve language teaching and testing.