The objectives of this research are to find out the correlation between (1) vocabulary mastery and writing skill; (2) self-esteem and writing skill; and (3) vocabulary mastery, self-esteem, and writing skill.
This research was carried out from December 2015-May 2016. This research used quantitative approach. The design used in this study was correlational study. The population was all the tenth grade students of SMAN 1 Tangen in the academic year of 2015/2016 consisting of six classes in the tenth grade, i.e.: XA, XB, XC, XD, XE, and XF. The total number of the students is 144 students. The sample was 22 students taken by cluster random sampling technique. The instruments in collecting the data were test and questionnaire. Objective test was used to collect the data of vocabulary mastery. Essay test was used to collect the data of writing skill. The questionnaire was used to collect the data of self-esteem. The techniques used to analyze the data were Single Correlation and Multiple Regression Correlation.
The results of the data analysis show that in the level of significance of a = 0.05 (1) there is a positive and significant correlation between vocabulary mastery and writing skill (????1??=0.6766 > rt=0.423); (2) there is a positive and significant correlation between self-esteem and writing skill (????2??=0.9874 > rt=0.423); and (3) there is a positive and significant correlation between vocabulary mastery, self-esteem, and writing skill (Rx1.2y=0.85964 and ??0=26.89 > ????=4.35).
Based on the results of this study, it can be concluded that there is a positive and significant correlation between (1) vocabulary mastery and writing skill; (2) self-esteem and writing skill; and (3) vocabulary mastery and self-esteem simultaneously and writing skill.
The results of this study reveal that vocabulary mastery and self-esteem are important factors that give contribution to writing skill. Both vocabulary mastery and self-esteem give 73.89% effective contribution to writing skill. Therefore, vocabulary mastery and self-esteem should be considered in increasing students' writing skill, although these factors are not the only variables determining writing skill. It is suggested that teachers create innovation in utilizing any interesting activity and develop lesson plan which enable students to acquire vocabulary easily and increase their self-esteem.
Keywords: correlation, self-esteem, vocabulary mastery, writing skill.