One of the themes that ran throughout all the presentations at the workshop was to know why we’re testing. And thus, to know why a given test is being developed (or selected). It’s important to know the purpose of testing in the first place. So, what are reasons people test bilinguals? What is it we need to know; and for what purpose?
Sometimes we need to know about a person’s language proficiency. I think of proficiency is how well someone knows a language, how good they are at it. This can be in the area of spoken language, written language, or both. It can also be focused on a single domain such as vocabulary or grammar. Reasons we may want to know about someone’s proficiency is to know if they are ready to move on to another level of language; or if a child for example is ready to handle an all-English classroom. We may use proficiency testing as a way to monitor rate of growth in learning a language. Proficiency testing requires testing against a standard level of proficiency or performance. If we know that a certain level is associated with success at a certain language demand or task, then we can interpret proficiency level in that way. In terms of looking at grown, we can use it to see if a program of language learning is effective. We can also use it to compare someone’s progress over time.
Language dominance is related to, but not exactly the same as proficiency. Dominance is relative to the other language. Maybe someone is equally dominant in two languages. But, they can be highly proficient in those languages or not proficient at all in those two languages. So, for proficiency, tests need to be comparable to each other in terms of difficulty and structure so that the two languages can be compared. These tests are usually used to figure out what language is stronger or better. This kind of testing often has implications for language of instruction or intervention.
Another reason bilinguals are tested is to determine underlying language ability. These tests need to focus on items that can gauge different levels of language ability. This is different from both proficiency testing and dominance testing, although I’ve sometimes seen these terms used interchangeably. Ability testing is trying to get at the question of whether someone has a learning or language impairment or delay. This is particularly difficult in testing bilinguals because low scores can be due to language of proficiency or because it’s the weaker language or because language ability is low. But, the test should specifically be designed to test ability rather than proficiency or dominance because you can’t interchange a test’s purpose. Unfortunately, since there are few tests for bilingual language ability often tests of proficiency or dominance are used for this purpose. This of course is a problem because that’s not what those tests were designed to do.