36 validity, the researcher conducted try-out test in Poetry I class A. In this research,
the test had three validity aspects. Those were content validity, construct validity, and face validity.
a. Content Validity
Content validity measures what students had learned before. It refers to “the appropriateness the content of the curriculum being studied” Bertrand and
Cebula, 1980: 112. The test really measures the students’ achievement in studying the materials being learned. Brown 2004:22 defines that a test can
claim content validity if the test itself samples the subject matter and requires the test taker to perform behavior being measured. To reach content validity, a test
must relate to the subject matter which is given before, represent the materials given before and stimulate the students to perform behavior as the response of
their learning experience relating to the test’s purposes. Since the research was about describe mastery of defining and non-
defining relative clauses by students of the English Language Education Study Program, the test that the researcher conducted could be claimed content validity
because the test related to the subject matter. The subject matter here referred to defining and non-defining relative clauses. The students learnt relative clauses for
four semesters in four levels of Structure class. The test also represented the materials about defining and non-defining relative clauses given and learnt in four
levels of Structure class. In addition, the test measured the students’ mastery of defining and non-defining relative clauses which was the test’s purpose.
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b. Construct Validity
Construct validity measures the students’ traits or qualities. According to Bertrand and Cebula 1980: 113, construct here means human traits or qualities.
In this aspect of validity, problem-solving behavior is a way to train the students’ intelligence and judgment. It refers to that students’ ability to solve their problem
indicates their quality of intelligence and judgment. Bertrand and Cebula 1980: 113 state behavior shows both “the existence and the quality of these cognitive
powers”. The cognitive powers here refer to intelligence and judgment. Considering the test’s purpose was to examine if the students master
defining and non-defining relative clauses or not, the test used in this research possessed two proofs proving that the test had construct validity. First, the
questions on the test were able to stimulate the students to perform their mastery of defining and non-defining relative clauses by choosing the correct relative
pronouns in order to construct the correct sentences using relative clauses. Second, the test was able to encourage the students to perform their
qualities in making decision whether the complex sentence containing a defining or a non-defining relative clause. If the complex sentence contained a defining
relative clause, they would not put commas to separate the relative clause from the main clause. On the other hand, if the complex sentence contained a non-
defining relative clause, they would put commas to separate the relative clause from the main clause.
Ellis and Barkhuizen 2005:51 cite that learner errors are significant when they serve pedagogical purposes, research purposes, and learning purposes.
38 Pedagogical purposes show what the learners learnt and have not yet understood.
In this research, the test was incidental test that the students had not yet known about the test. The test also was not conducted in Structure class, but in Poetry I
class for try-out test and Academic Essay class so there was no preparation for the test. Having test without any preparation could minimize making mistakes. It
proved that the incorrect answers in the test served pedagogical purposes. The researcher had three reasons to make sure that most of the incorrect answers were
errors, not mistakes. Research purposes provide evidence of language learning process. In the
research, the test was conducted in the morning. The students came to the class just to submit their paper and there was no lecture too so the students’ condition
was still fresh. This condition could also minimize appearing mistakes in the test. It was an evident that the incorrect answers in the test provided research purposes.
Learning purposes show the rules of the target language. In the research, the students had learnt relative clauses in four levels of Structure class for four
semesters. Therefore, they should possess sufficient understanding of relative clauses. Learning rules of target language regularly for four semesters were able
to minimize occurring mistakes in the test too. It gave an evident that the incorrect answers in the test performed learning purposes.
c. Face Validity
