Matakuliah : G0444 / MATERIAL DESIGN and TESTING
Tahun
: 2009
Pertemuan 23
VALIDITY
A test is said to be valid if
it measures accurately what it is intended to measure.
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The concept of validity reveals a number of aspects :
A. CONTENT VALIDITY
B. CRITERION RELATED VALIDITY
C. CONSTRUCT VALIDITY
D. FACE VALIDITY
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A. CONTENT VALIDITY
A test is said to have content validity if its content constitutes a
representative sample of the language skills, structures, etc with
which it is meant to be concerned.
E.g., a Grammar test must be made up of items testing knowledge or
control of grammar. But this in itself doesn’t ensure content validity. The
test would have content validity only if it included a proper sample of the
relevant structures. Just what are the relevant structures will depend upon
the purpose of the test. ( A test for intermediate learners is not the same as
a set of structures for advanced learners ).
In order to judge whether or not a test has content validity, we need a
specification of the skills or structures, etc that it is meant to cover. Such a
specification should be made at a very early stage in the test construction.
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What is the importance of content validity ?
1.
The greater a test’s content validity, the more likely it is to
be an accurate measure of what it is supposed to measure.
2.
A test which doesn’t represent items in the specification is
likely to have a harmful backwash effect. Areas which are
not tested are likely to become areas ignored in teaching and
learning. Too often the content of tests is determined by
what is easy to test rather than what is important to test.
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B. CRITERION-RELATED VALIDITY
To see how far results on the test agree with those provided by
some independent and highly dependable assessment of the
candidate’s ability. This independent assessment is thus
criterion measure against which the test is validated.
There are two kinds of criterion-related validity :
1. Concurrent Validity: it is established when the test and the
criterion are administered at the same time.
2. Predictive Validity: it concerns the degree to which a test can
predict candidate’s future performance.
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C. CONSTRUCT VALIDITY
A test, part of a test or a testing technique is said to have
construct validity if it can be demonstrated that it measures just
the ability which it is supposed to measure.
The word “construct” refers to any underlying ability (or trait) which is
hypothesized in a theory of language ability.
For example, one might hypothesize that the ability to read involves a
number of sub-abilities (such as: ability to guess the meaning of unknown
words from the context). If we attempted to measure that ability in a
particular test, then that part of the test would have construct validity only
if we were able to demonstrate that we were indeed measuring just that
ability.
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Construct validation is a research activity, the means by which
theories are put to the test and are confirmed, modified, or
abandoned. It is through construct validation that language
testing can be put on a sounder, more scientific footing.
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D. FACE VALIDITY
A test is said to have face validity if it looks as if it measures
what it is supposed to measure.
For example a test which pretended to measure pronunciation ability but
which did not require the candidate to speak might be thought to lack face
validity.
Face validity is hardly a scientific concept, yet it is very important. If a test
doesn’t have face validity, it may not be acceptable to the students taking it,
teachers, or education authorities; and if it is used, the students may not
perform on it in a way that truly reflects their ability.
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