Validity-Realiability-Practicality-Backwash effects:

Validity

A test it said to be valid if it measures correctly and precisely what is intended to be measure.
In order to prove tests validity, we have to consider several factors to reveal its relationship between the test and the performance is intended to demonstrate.

Content Validity: represent the entire range of possible items the test should be cover correctly and appropriately.

Criterion-related validity: demonstrates the degree of effectively in predicting criterion or indicators of a construct.

The following are two kinds of criterion-related validity:

•Concurrent validity: when the test and criterion more or less have been done at the same time.
•Predictive validity: when test can predict future success.

Reliability

Factors in the test are consistent. Therefore if a student takes a test today but also takes the same test tomorrow, if the results come out more or less the same, we consider the test is reliable.

Practically

Concerned or well related to all actual intend and purposes of the test.

Achieving a beneficial Backwash

Backwash is the effect tests have on learning and teaching. Backwash will result better understanding of the process involved and how different variables can contribute on its effect in different situations, it could be positive or negative backwash effect.

Do you know if the tests you have been using or done are valid, reliable, and practical or if they have a negative or positive backwash effect in teaching and learning?
In my experience the small amount of test I have taken in my career have been valid, reliable, practical and had a positive backwash my learning, and in a future in teaching also.