SUMMARY OF PRACTICALLY, RELIABILITY, AND VALIDITY

1.PRATICALITY

An effective test is practical is meant that  is not excessively expensive,stays within appropriate time constrains, is relatively easy to administer, and has a scoring/evaluation procedure, that is specific and time-efficient. A test of language proficiency that takes a student five hours to complete is impractical-it consumes more time(and money) than necessary to accomplish its objective. A test that can be scored only by computer is impractical if the test takes  place a thousand miles away the nearest computer. In classroom-based testing, time is almost always a crucial practicality factor for busy teachers with too few hours in the day.

2.REABILITY
A reliable test is consistent and dependable. If you give the same student or matched student on two different occasions, the should yield similar. reliability of a test may best be addressed by considering mnumber of factors that may contribute to the unreliability of a test.  A reliable test is consistent in its conditions across two more administrations; gives clear directions for scroring/evaluation; has uniform rubrics for scoring /evaluation ;lends itself to consistent application of those rubrics by the scorer ;contains items/tasks that are unambiguous to the task-taker.

3. VALIDITY

A valid test of reading ability actually measure reading ability. -not 20/20 vision, nor previous knowledge in a subject, nor some other variable of questionable relevance. How is the validity of a test established? There is no final, absolute measure of validity, but several different kinds of evidence may be invoked in support. In some cases, it may be appropriate to ex3.mine the extent to which a test calls for performance that matches that of the course or unit of study being testedAnother way of understanding content validity is to consider the difference between direct and indirect testing. Direct .testing involves the test-taker in actually perfonning the target task. Validity is a complex concept, yet it is indispensable to the teacher's understanding of what makes a good test. If in your language teaching you can attend to the practicality, reliability, and validity of tests of language, whether those tests are classroom tests related to a part of a lesson; fmal exams, or profiCiency tests, then you are well on the way to making accurate judgments about the competence of the learners with whom you are working.

4.AUTHENTICITY

Bachman and Palmer, (1996, p. 23) define authenticity as "the degree of correspondence
of the characteristics of a given language test task to the features of a target language task," and then suggest an agenda for identifying those target language tasks and for transforming them into valid test items.

In a test, authenticity may be 'present . in the following ways:
The language in the test is as natural as possible.
Items are contextualized rather than isolated.
Topics are meaningful (relevant, interesting) for the learner.
Some thematic organization to items is provided, such as through a story line
or episode.
Tasks represent, or closely approximate, real-world tasks.

5.WASHBACK

In large-scale assessment, washback generally refers to the effects the tests have on instruction in terms of how students prepare for the test. The challenge to teachers is to create classroom tests that serve as learning devices through which washback is achieved. washback also implies that students have ready access to you to discuss the feedback and evaluation you have given. While you almost certainly have known teachers with whom you wouldn't dare argue about a grade, an interactive, cooperative, collaborative classroom nevertheless can promote an atmosphere of dialogue between students and teachers regarding evaluative judgments. For learning.to continue, students need to have a chance to feed back on your feedback, to seek clarification of any issues that are fuzzy, and to set new and appropriate goals for themselves for the days and weeks ahead..





Source :
 Brown, H. G. (2004) Language Assessment : Principle and Classroom Practice.   
New York : Longman.