An ELT Glossary : Face validity
Face validity concerns the extent to which a test appears valid - ie appears to be "a good test" to the people using it - the learners taking the test, their parents, the teachers and institutions putting them in for the test etc.
As these people may not be testing experts, they may of course not fully understand what is involved. As an example: if you look at the example given under construct validity, you will see that there are various reasons why dictation is not a valid test of listening comprehension. Yet many learners (and teachers) who are used to it as an activity type may accept quite happily that listening ability should be tested in this way, and make no objection to a test which includes it.
This means that a test which has face validity is not necessarily a good test - and similarly a test which does not have face validity is not necessarily a bad test. However, despite this, it is an important quality for a test to have. If a test, which may possess every other quality required - other forms of validity, reliability, practicality or whatever - does not have face validity, then learners are not going to want to take the test or be happy that its results are a fair assessment of their language competence.
Related terms : validity, content validity, predictive validity,