The objectives of this research are to find out the correlation between (1) students’ self-efficacy and writing skill; (2) students’ grammatical competence and students’ writing skill; and (3) students’ self-efficacy, students’ grammatical competence, towards students’ writing skill.
This research used quantitative method that is correlational study. The study was carried out in January 2015 at SMA Negeri 1 Karanganom, Klaten. The population was all the eleventh grade of SMA Negeri 1 Karanganom, Klaten in the academic year of 2014/2015) which consists of ten classes. The total number of the students was 315 students. The sample was 31 students taken by cluster random sampling technique. The instruments in collecting the data were questionnaire and test. The questionnaire was used to collect the data of students’ self-efficacy; while the objectives test was used to collect the data of students’ grammatical competence and students’ writing skill. The techniques which were used to analyze the data were Single Correlation and Multiple Correlation.
The results of the data analysis show that in the level of significance a = 0.05 (1) there is a positive correlation between students’ self-efficacy and students’ writing skill (rx1y = 0.4370366 > rt = 0.355); (2) there is a positive correlation between students’ grammatical competence and students’ writing skill (rx2y = 0.87139 > rt = 0.355); and (3) there is a positive correlation between students’ self-efficacy, students’ grammatical competence, and students’ writing skill (Ry12 = 0.873 and Fo = 45.041 > Ft = 3.34).
Based on the result of the study, it can be implied that self-efficacy and grammatical competence are important factors that give contribution to students’ writing skill. Both self-efficacy and grammatical competence have positive contribution in writing skill, it is 76.30%. Therefore, students’ self-efficacy and students’ grammatical competence should be considered in increasing students’ writing skill, although the factors not only come from those variables.
Keywords: Correlation, Self-efficacy, Grammatical competence, Writing skill