referred to an error as a breach of the code. Error deviates from what is regarded as the
norm. According to James (1998), he calls error "deviant". Intentionality plays a decisive
role in this definition. James calls them deliberate errors because they do not exist. There
are four categories concerning his term: grammaticality;  acceptability; correctness;
strangeness infelicity. The third term "correctness" refers to the prescriptive standard. This
may confuse people by the similarity with grammaticality.
 
1.1.2 Lexical Errors
For some learner groups, vocabulary acquisition  is one of the most important factors that
affect the writing proficiency of Chinese students, especially the college students. Therefore,
lexis has begun to take a central role in language study. There are a number of reasons for
this. First, the boundaries between lexis and grammar are now seen to be less clear-cut than
was assumed. Morphological aspects of words, which used to be treated as part of grammar,
can just as well be viewed as part of the word. This is particularly true of derivational
morphology, whereby words of different form classes can be derived from the same root:
adjective  bright---noun  brightness---adverb  brightly. Also, many lexical items consist of
more than one word, and have leg or kick the bucket, the integrity of which is easily shown
by the impossibility of pluralizing the noun in each. Secondly, learners themselves believe  
that vocabulary is very important in language learning.   
Everyone makes errors.  However, errors can provide information about the process of
acquisition. As a result, there are good reasons for focusing on errors. First, they are  
raising the important question of "Why do learners make errors?" Second, it is useful for
teachers to know what errors learners are likely to make. Third, paradoxically, it is possible
that making errors may actually help learners to learn when they self-correct the errors they
make.
 
As a result, this study aims to investigate errors in students' writings. As we know, among
the four skills in language learning, writing is  usually considered to be the last acquired
skills because it is the most difficult one to process. However, writing is also required at
each learning stage from junior middle school to the university. And the learners are
required to express their ideas clearly and grammatically. However, writing ability is the
most difficult skill and learners are usually found to be very weak in their writing ability. It
is really surprising that learners still make so many errors even though they have learned
English for so many years. As a result, experts imply to take proper measures to help
students to reduce errors in writing. In order to achieve this goal, lexical analysis
concerning these errors should be conducted.
 
By describing and explaining these errors we may work out the countermeasures to help
students reduce them in writing so that the quality of their writing may be improved. At the
same time, some suggestions for language teaching are put forward.
 
1.2 Methods of Study
The research methods this study has adopted mainly includes quantitative approach and  
qualitative approach. One hundred and twenty freshmen in Nanjing University of Science
and Technology were selected as the subjects. All of them are non-English majors and most
of them passed CET-4. The subjects were required to write one composition. Then 120
compositions are collected and analyzed. When analyzing students' writings, there are many   
kinds of errors, such as lexical errors, syntactic errors, and discourse errors and so on. This 非英语专业学生英语写作中的词汇错误分析与对策(2):http://www.youerw.com/yingyu/lunwen_4257.html