This paper is an attempt to explain the concept of validity, since it is related to the most important issues in language testing. Chapter I will give the introduction of characteristic of a good test in validity. Validity, for many scholars (e.g. Shonamy 1994), is a complex issue. In the light of this state, Chapter II is going to consider the types of validity itself, they are content validity, face validity, construct validity and empirical validity. Finally, as usual, the conclusion will summarise the paper.
CHARACTERISTICS OF A GOOD TEST:
The definition of the validity:
Alderson, Clapham and Wall (1995:179) cite Henning’s definition of validity as following:
“Validity in general refers to the appropriateness of a given test or any of its component parts as a measure of what it is purported to measure. A test is said to be valid to the extent that is measures what it is supposed to measure. It follows that the term is valid when used to describe a test may be valid for some purpose, but not for other”
In another source, it is said that Validity is the most important consideration in test evaluation. The concept refers to the appropriateness, meaningfulness, and usefulness of the specific inferences from the test scores. Test validation is the process of accumulating evidence to support such inferences.
1. Content Validity
It is, Kerlinger (1973:458) cited in Alderson, Clapham and Wall (1995:173), the representative or sampling adequacy of the content–the substance, the matter, the topic–of a measuring instrument. Usually, content validity is based on the experts’ assessment. Based on Robert and Norman (1995 : 50) content validity is how well the sample of assessment tasks represents the domain of task to be measured.
In the light of previous definition, content validity can be assessed. Ferguson (2006:2) by attempting to answer following questions:
• Is what candidates are asked to do relevant to their future work instrument?
• Is there a match between the characteristics of the test takers and the characteristics of the target language use situation?
• Does the test test what is contained in the syllabus?
• How relevant is the test content-to the needs of the students; to the syllabus?
Does the test content offer a good basis for inferences about canididate’s ability in the target language use domain?
2. Face Validity
Face validity is concerned with the extent to which the contents of a test or procedure look like they are measuring what they are supposed to measure.
This is validated using common-sense rules. A test that does not have face validity may be rejected by test-takers (if they have that option) and also people who are choosing the test to use from amongst a set of options.
3. Construct Validity
Construct validity is how well performance on the assessment can be interpreted as a meaningful measure of some characteristic or quality. The procedure is experimentally determine what factors influence scores on the test.
Empirical validity describes how closely scores on a test correspond (correlate) with behavior as measured in other contexts. There are two kinds of empirical validity:
a. Concurrent validity
Concurrent validity is demonstrated where a test correlates well with a measure that has previously been validated.
b. Predictive validity
Predictive validity, according to Alderson, Clapham and Wall (1995) and Ferguson (2006), has a special attention in the field of proficiency tests (e.g. IELTS, TOEFL…etc) where the aim is to predict how one will do in the future (e.g. in university, jobs…etc).
The focus of both types of studies will be shown in the following figure, is on determining the extent to which test performance is related to some other valued measure of performance. As noted earlier, the second measure of performance may be obtained at some future date (when we are interested in predicting future performance) or to concurrently (when we are interested in estimating present performance).
The most important quality to consider when constructing or selecting an assessment procedure is validity, which refers to the meaningfulness and appropriateness of the uses and interpretations to be made of assessment results. Different aspects of validity in characteristic of a good test has been considered in this paper. There are four types of validity such as content validity, face validity, construct validity and empirical validity.
Alderson, C; Clapham, C and Wall, D. Language Test Construction and Validation. Cambridge: CUP. 1995.
Ferguson, G. Handout: ‘Lecture on the Validity and Validation’ in University of Sheffield. 2006.
Norman E., Measurement and Evaluation in Teaching, Fourth Edition. New York:
Macmillan Publishing Co. Inc.. 1981.
Robert L., and Norman E.. Measurement and Assessment in Teaching, Seventh Edition.
New Jersey: Prentice Hall. 1995.