2、Validity and IELTS
　　It is essential to keep test validity in mind when designing an ITLTS listening test in order to get a successful outcome. The validity of test is the extent to which it measures what it is supposed to measure (Heaton, 2000, p.157). A test is said to be valid to the extent that it measures accurately what it is supposed to measure (Arthur, 2000, p.22). Any test may be valid for some purposes, but not for others (Henning, 1987, p.89). IELTS, the International English Language Testing System, is jointly managed by the University of Cambridge ESOL Examinations, British Council and IDP: IELTS Australia (Jakeman & McDowell, 2002, p.5). IELTS is available in Academic and General Training formats, in both formats, candidates are tested in listening, reading, writing and speaking (The British Council, 2001, pp.4-5). All candidates take the same Listening modules. Designing an IELTS listening test is complex and demanding. There are many considerations to ensure test validity in designing an IELTS listening test, this paper focuses on three mian considerations: the purpose of the test, test specifications, and content authenticity.
　　3、The purpose of IELTS listening test
　　Making clear of the purpose of the test is the essential step in designing an IELTS listening test. The prime consideration for the development of any test is that of purpose (Spaan, 2006), Validity can be established in a number of different ways (Alderson, Clapham & Wall, 2000, p.171). Content validity and construct validity are more important than other aspects of validity, every effort should be made in constructing the test to ensure content validity (Arthur, 2000, pp.26-27). A test would have content validity only if it included a proper sample of the relevant structures, while relevant structures depend upon the purpose of the test (Arthur, 2000, p.22). Content validity depends on a careful analysis of the language being tested and of the particular objectives (Heaton, 2000, p.160).
Specific characteristics of IELTS shape the purpose of IELTS listening test. Firstly,
　　IELTS is designed to assess the language ability of candidates who need to study or work where English is the language of communication; the academic module assesses whether a candidate is ready to study or train in the medium of English at an undergraduate or postgraduate level, while the general training module emphasizes basic survival skills in a broad social and educational context (Adams & Peck, 2001, pp.5-7). Secondly, IELTS is a proficiency test, which is not based on a particular language program, it is designed to test ability of students with different language training backgrounds (Alderson et al, 2000, p.12). When designing an IELTS litening test, test writer need to take all these characteristics into account carefully.
　　4、Test specifications
　　Test specifications should be made at a very early stage in IELTS listening test construction. Test specifications are the blueprint to be followed by test writers, the development and publication of test specifications is a central and crucial part ofthe test construction and evaluation process (Alderson et al, 2000, p.9). Test specifications are important to ensure content and construct validity. On one hand, to write full test specifications and to ensure that the test content is a fair reflection of these are important to test (Arthur, 2000, pp.22-23), every effort should be made in constructing tests to ensure content validity (Arthur, 2000, p.27). In order to judge whether or not a test has content validity, we need a specifications of the skills or structures (Arthur, 2000, p.22). On the other hand, test specifications provide the statement about what the test tests and how it tests it, they are essential in the establishment of the test's construct validity (Alderson et al, 2000, p.9). When embarking on the construction of a test, the test writer should first draw up the test specifications, describing in very clear and precise terms the particular language skills and area to be included in the test (Heaton, 2000, p.160).
　　Test specifications should include the information on language skills to be measured, content, format and timing, criteria levels of performance, scoring and reporting system (Arthur, 2000, pp.48-49). More attention should be paid to the first two aspects when designing IELTS listening test. Firstly, according to the purpose of IELTS, skills assessed in listening test should cover the skills used both in social and academic situation. Secondly, the content of IELTS listening test should be designed according to the purpose of the test and skills to be assessed. Candidates need to listen to a number of recorded texts including a mixture of monologues and conversations. Recording should cover passages concerned with social needs, for example, the dialogue between two speakers about travel arrangements or decisions on a night out, the recording monologue about student services on a university campus or arrangements for meals during a conference (Adams & Peck, 2001, p.6); meanwhile, as academic module aims to assess test takers' ability of studying abroad, test recording should include passages concerned with situations related more closely to educational or training contexts, for example, a conversation between up to four people and then a further monologue, a conversation between a tutor and a student about an assignment or between three students planning a research project, and a lecture or talk of general academic interest (Jakeman & McDowell, 2007, pp.6-7). (责任编辑：南粤论文中心)转贴于南粤论文中心: http://www.nylw.net(代写代发论文_毕业论文带写_广州职称论文代发_广州论文网）