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20. What is item analysis?
What is the facility value of an item?
What is its discrimination index?
Item analysis is for judging the value of items in norm-referenced testing. The main information to be obtained about individual items (e.g. Multiple Choice or True / False) is ITEM DIFFICULTY and ITEM DISCRIMINATION.
ITEM DIFFICULTY - finding out the % of people who get the item right in the try-out group.
In norm-referenced testing, one rejects items which are too easy or too difficult because the purpose is to discriminate.
The difficulty of an item = its FACILITY INDEX: % who give the right answer. The usual aim of the test setter is to achieve even to middling facility indices ranging from about 40-60%.
The DISCRIMINATION of an item is judged by comparing those individuals who succeed on a given item with those who score highly on the test as a whole:
Discrimination for any given item = [Correct Tops - Correct Bottoms] / 1/2 Number of students
21. What are the main difficulties and limitations of language testing?
The state of knowledge of Language & Language Learning. Content validity: does what we are testing represent language? Does it match up to the goals of language learning and the objectives of the language learner?
Difficulties in testing Communicative Competence / Interaction - administrative difficulties.
Objective and Norm-referenced tests tend to point towards measures of receptive learning. Learners don't have to produce language in many of these tests. Validity/Reliability tension.
Advantages: Actual marking is easy. Can be done mechanically or by overlay. Can be pre-tested. Test population. Compared over different years. These tests are not as objective as the marking system suggests.
A good deal of judgement has been used in developing & setting them re rejection or acceptance of items. They also invite guessing (No of alternatives = 4 or 5 for each item.
A much wider sample of grammar, vocabulary & phonology can generally be included in an objective test than a subjective one, but objective tests can never test ability to communicate in the target language, nor can they evaluate actual performance.
Objective tests tend to test receptive learning. The students may produce no language at all.