2. Criteria for Evaluating Students’ Writing Ability

3.7.2. Reliability Reliability of Test

Reliability refers to extend to which the test is consistent in its score and gives us an indication of how accurate the test score are Shohamy, 1985:70. In achieving the reliability of the pretest and posttest of writing, interrater reliability was used in this study. It needed some researchers as a team; moreover, the researchers must determine the test and the criteria of the test before gathering the data Setiyadi, 2006:19. The first rater was the researcher herself and the second rater was the research’s partner who was the college students of English study program. In achieving the reliability of pretest and posttest of writing test, first and second raters discussed and put mind of the writing criteria in order to obtain the reliable result of the test. The researcher also used the statistical formula for counting the reliability score between the first and second raters. The statistical formula of reliability was as follow: R= 1 R = Reliability N = Number of students d = the different of rank correlation 1-6 = Constant number After finding the coefficient between raters, the researcher analyzed the coefficient of reliability with the standard of reliability below: a A very low reliability range from 0.00 to 0.19 b A low reliability range from 0.20 to 0.39 c An average reliability range from 0.40 to 0.59 d A high reliability range from 0.60 to 0.79 e A very high reliability range from 0.80 to 0.100 Slameto,1998: 147 in Hayanti, 2010:38 The result of inter-rater reliability of the pretest was 0.962 and the posttest was 0.969; those showed the very high reliability 0.80 to 0.1. The first rater and the second rater put the score of the students’ works in each aspect of writing S’ code Content Organization Vocabulary Language use Mechanics Total R1 R2 R1 R2 R1 R2 R1 R2 R1 R2 R1 R2 1 2 Reliability of Observation Observation can be seen as an instrument of qualitative research. In order to get the reliability of this instrument and the data, the researcher did participant obser- vation. Participant observation is the process enabling researchers to learn about the activities of the people under the study in the natural setting through observing and participating in those activities Kawulich, 2005. Bernard as stated by Kawu- lich 2005 believes that participant observation as the process of gaining infor- mation by learning to act in such a way as to blend into the community so that its