Reliability, Validity and Practicality

Reliability, Validity and Practicality

How do you know if a test is effective? if you want to know the answer to that questions, you have to respond these questions about the test itself:

  1. Can I apply the test within appropiate administrative constraints?
  2. Does the test measure what you are trying to measure?
  3. Can the test be score by different teachers and yield similar results?

If you can answer positively to those three and other related questions, your test is an effective test or in other words your test is reliable, practical and valid.

Are Your Test Reliable, Valid and Practical

Let’s explore those concepts of reliability, validity and practicality a little bit more

#1 Reliability

A reliable test means that it should give the same results for similar groups of students and with different people marking.

  1. Keep the instruction language simple and give an example.
  2. Use language that is similar to what you’ve used in class, so as not to confuse students.
  3. If possible, ask a colleague to do the test before you use it with students.
  4. For testing productive skills such as writing and speaking, have two markers and use standard written criteria.

There are factors that contributes to the unreliability of a test such as:

  • Student-related reliability which can be caused by fatigue, sickness, anxiety.
  • Rater Reliability which can be caused by subjectivity, bias and human error
  • Test Administration Reliability which can be caused by the conditions in which a test is administered
  • Test Reliability which is caused by the nature of a test. Long tests can cause fatigue

#2 Validity

Validity is the extent to which a test measures what it claims to measure. To make a valid test, you must be clear about what you are testing.

Always test what you have taught and can reasonably expect your students to know.

Check these two examples that illustrate the concept of validity well.

  • To test writing with a question where your students don’t have enough background knowledge is unfair.
  • Testing speaking where they are expected to respond to a reading passage they can’t understand will not be a good test of their speaking skills.

#3 Practicality

Practicality in assessment means that the test is easy to design, easy to administer and easy to score.

No matter how valid or reliable a test is, it has to be practical to make and to take this means that:

  1. It is economical to deliver. It is not excessively expensive
  2. The layout should be easy to follow and understand.
  3. It stays within appropriate time constraints
  4. It is relatively easy to administer
  5. Its correct evaluation procedure is specific and time-efficient

Characteristics of impractical tests are:

  1. these test are excessively expensive
  2. they are too long
  3. they require a handful of examiners to administer and score
  4. it takes several hours to grade a test
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