THE EFFECTS OF VOCABULARY AND GRAMMAR MASTERY ON STUDENTS’ WRITING SKILL

Writing is not just production of text. It is also process of learning and trying out the ideas to choose the proper words with correct grammatical rules. The objective of the research is to know the effects of vocabulary and grammar mastery on students’ writing skill. This research used survey method with total sample of the research is 40 students. The data were collected by giving three sets of objective test as the instruments to the 40 students. The data analysis technique of the research is multiple linear regression analysis. The research findings show: 1) There is a significant effect of vocabulary and grammar mastery simultaneously on students’ writing skill. 2) There is a significant effect of vocabulary mastery on students’ writing skill.. 3) There is a significant effect of grammar mastery on students’ writing skill.


Introduction
As an international language, English is chosen as the first foreign language to be taught in Indonesian formal education from elementary school until college or university. Consequently, it is very essential for students to master English which includes four language skills: listening, speaking, reading and writing skills. Writing functions as the handmaid of the three other skills (Rivers, 1981). Writing is a process which requires students to practice often because there are many components that can make writing have good quality. Lecturers frequently ask students to produce a text in order to assess their writing skill. The text refers to a collection of sentence patterns and vocabulary items (Silva, 1990). Whereas, writing is not just production of text; it is also learning and trying out the ideas on papers to choose the proper words. That is why students need to enrich their vocabularies. Vocabulary is a component of language that contains all the information about the meaning and use of the words (Jamhuri, 2021). Therefore, vocabulary is considered vital part of effective communication (Langan, 1993) and is recognized as an essential factor in writing. Several textbooks provide materials about writing skill and how to develop it. They talk about type of writing used in university courses or other English language institutions of higher education (Zemach & Rumisek, 2003). They also highlight the importance of students' awareness of the impact of their words choices, sentences, and organizational techniques on the effectiveness of their writing (Randaccio, 2013). In other words, vocabulary mastery is needed to help students use each word appropriately in producing good writing. Vocabulary mastery refers to someone's ability in using words and their meaning properly in language (Yuliawati, 2018). Consequently, students should explore and enlarge their vocabularies to enhance their writing quality. Moreover, fluency in writing should not to be confused with grammatical accuracy (Randaccio, 2013). It means, students need to develop both. Grammar means a set of syntactically valid information rules of a formal language (Jamhuri, 2021). It is concerned with how sentences and utterances are formed (Thornbury, 2002). Since writing is a process, students need to practice a lot. They have to learn grammatical aspects as the fundamental organizing principle of language. Learning English grammatical is done as a basic for learning language such as tenses, subject-verb agreement, proper used of conjunction, parallel structure, kind of sentences, sentence pattern, etc. Good grammar reflects good writing. Thus, in order to improve their writing skill, students should also have good grammar mastery. Grammar mastery means the ability to understand the theory of sentence such as functions, units, or forms and the ability to produce standard forms in accordance with the rules and regulations (Yuliawati, 2018). Unfortunately, several existing researches on grammar teaching have a limitation, which is there is no clear conceptualization of a theoretical rationale for why grammar might support writing development (Jones, Myhill, & Bailey, 2013). The theoretical connection between grammar and writing has not been sufficiently explained (Myhill, 2010). For the explanations above, the researcher would like to have a survey study to know exactly about the effects of vocabulary and grammar mastery on students' skill in writing text. Hopefully, this research can give lecturers idea about how to help students improve their writing skills and encourage students to practice their vocabulary, grammar, and other language components to enhance their writing skill as well.

Research Methodology Research Design
The method used in this research is survey method. There are three variables in this research: vocabulary mastery and grammar mastery as the independent variables and writing skill as the dependent variable. The hypothesis testing was analyzed by using multiple linear regressions. The research design can be seen in the following scheme: Figure 1

. Research Design
Description: X1 : Vocabulary Mastery X2 : Grammar Mastery Y : Writing Skill Population and Sample The population in this research was the second semester students of Universitas Bina Sarana Informatika majoring Communication Science who was taking Advance English Course in academic year 2020/2021. In this research, the researcher used probability sampling. According to (Ary, Jacobs, Sorensen, & Razavieh, 2010), probability sampling is defined as the kind of sampling in which every element in the population has an equal chance of being selected. Cluster sampling is one of the types of probability sampling. In cluster sampling, the unit chosen is not an individual but, rather, a group of individuals who are naturally together. As a result, 40 students were used as the samples in this survey research.

Data Collection Technique
The data were collected by giving three sets of objective test as the instruments to the 40 students. Test 1 and Test 2 were given to assess students' vocabulary and grammar mastery, while Test 3 was given to assess students' writing skill. Both Test 1 and Test 2 consisted of 30 questions in the form of multiple choices, whereas Test 3 was task to write a recount text. Here, students are asked to write recount text because they got this material in Advance English X1 X2 Y Course.

Data Analysis Technique
The hypothesis test used multiple linear regressions, and the overall analysis was carried out by a computer program of SPSS version 20.0 for windows.

Findings and Discussion Research Findings
The recapitulations of the entire test can be seen in the set of following tables:

The Effects of Vocabulary (X1) and Grammar Mastery (X2) Simultaneously on
Students' Writing Skill (Y) Referring to table 1 above, it can be seen that the coefficient correlation of the effect of vocabulary and grammar mastery simultaneously on students' writing skill is 0.858. It indicates that among variables has very strong effect because Ro is close to 1. Meanwhile, the coefficient of determination of vocabulary and grammar mastery variables on writing skill is 0.674. It means that the contribution of vocabulary and grammar mastery simultaneously on students' writing skill is 67.4% and the rest (32.6%) is determined by other factors. According to table 2 above, we can see that Sig. = 0.000 < 0.05 and Fo = 51.932 which means there is a significant effect of vocabulary and grammar mastery simultaneously on students' writing skill. According to table 3, we may set the regression line equality that represents the effects of vocabulary mastery (X1) and grammar mastery (X2) on students' writing skill (Y) in the following equation: : dependent variable X : independent variables Explanation: a. The value of constant is 15.447. It means if the independent variables are considered constant, the students' writing skill value is 15.447. b. The value of regression coefficient of Vocabulary Mastery (X1) is 1.894. It means that each addition of one unit of vocabulary mastery will have an impact on the increased students' writing skill in the amount of 1.894. c. The value of regression coefficient of Grammar Mastery (X2) is 0.867. It means that each addition of one unit of grammar mastery will have an impact on the increased students' writing skill in the amount of 0.867. By having a good vocabulary, it does not mean that students would be able to write the recount text automatically. It must be enhanced by grammar mastery so that they would be able to write down the recount text as well. Writing is the act of producing a text by following grammatical rules, lexical items, and rhetorical patterns. But, producing good writing is more than obeying grammar rules. It is also the art of using rhetoric, of arranging words, phrases, sentences, and paragraph. (Randaccio, 2013) mentioned some features relevant to the writing process, among others grammar, appropriateness of vocabulary, language, punctuation, organization, and syntax. Vocabulary mastery and grammar mastery are two important elements to perform the communicative productive skill, especially in writing. One's success in writing recount skill will be determined by those factors. In order to produce good writing, students should be aware of the importance of building a large vocabulary and produce grammatically correct sentences. Overall, both quantitative information and theoretical review above, we can see that vocabulary and grammar mastery simultaneously have positive and significant effect on students' writing skill in producing a recount text.

The Effects of Vocabulary mastery (X1) on Students' Writing Skill (Y)
Refering to table 3 above, it can be seen that Sig. = 0.000 < 0.05 and to = 6.611. It means that there is a significant effect of vocabulary mastery (X1) on students' writing skill (Y). Some other researches with the same focus and variables have similar results with this research. (Viera, 2017) found that vocabulary provides learners a broader ability to produce wellstructured written texts and tributes to the comprehension of utterances as well. (Hasan & Subekti, 2017) also conclude that there are significant correlations between vocabulary mastery and writing text ability. To be able to produce a good piece of writing, students should be able Ý = 15.447 + 1.894X1 + 0.867X2 to write a connected series of words and sentences which are grammatically and logically linked, so that the readers will understand the meaning intended by the writer. The importance of vocabulary is also stated by some experts like (Richards, 2002) who stated that vocabulary is one of the most noticeable components of language and one of the first things got attention from applied linguist. (Gairns & Redman, 1986) explained that vocabulary cannot be separated from listening, speaking, reading, and writing. In writing, the writer explores his/her vocabulary to develop idea by choosing appropriate words clearly and accurately. Without knowing much vocabulary, students cannot write successfully (Cameron, 2001) because we are limited on vocabulary mastery (Mahmudah, 2014). By having good vocabulary mastery, students will be able to choose more appropriate words and adapt their writing for various types of audiences. Besides, they also will be able to create interesting writing without using monotonous words. From both the research result, previous research, and theoretical review above, the researcher comes to the conclusion that vocabulary mastery may bring positive and significant effect on the students' writing skill. The higher the level of vocabulary mastery possessed by the students, the higher students' writing skill. Therefore, the researcher thinks that vocabulary mastery should be gained by students through some efforts such as reading English text or using vocabulary application available on mobile phone because it relatively makes learning vocabulary easier.

The Effects Grammar Mastery (X2) towards Students' Writing Skill (Y)
Refering to table 3 above, it can be seen that Sig. = 0.000 < 0.05 and to = 9.677. It means that there is a significant effect of grammar mastery (X2) on students' writing skill (Y). Grammar is a description of the structure of a language and the way in which liguistic units such as words and pharases are combined to produce in the language. To speak about grammar mastery is to speak about tenses because grammar mastery includes tenses. There are several kinds of tenses in English grammar. Tense is one of the elements in English that is relatively difficult to be understood and mastered by the students because there is no tense in Indonesian grammar. As we know one cannot write well without knowing how to distinguish the kind of tenses in grammar used. The knowledge about grammar, especially tenses, is mostly needed to develop writing style. Meanwhile, recount is a text, which retell series of events in the past. Recount relates a series of events and tells the reader about something that has happened to the writer or someone else in the past. As the result, writing skill in recount text is the ability to express the idea of retelling something/events which happened in the past. In writing a recount text, students have to use appropriate tenses too. Thus, they will require the grammar mastery to maintain the paragraph they are writing. In other words, students should possess the grammar mastery well if they want to convey the skill in writing as well. From both the research result and theoretical review above, the researcher comes to the conclusion that grammar mastery may bring positive and significant effect on the students' writing skill. The higher the level of grammar mastery possessed by the students especially correlated to writing domain, the higher the possibility to achieve the ability in writing. Hence, the researcher thinks that an interesting technique in teaching grammar should be developed by the English lecturers, so that students can enjoy the learning process and their writing skill can be improved.

Conclusion
From the findings and discussions above, some conclusions of this research can be presented as follows: 1. There is a significant effect of vocabulary and grammar mastery simultaneously on students' writing skill. 2. There is a significant effect of vocabulary mastery on students' writing skill. 3. There is a significant effect of grammar mastery on students' writing. This research is still very short in detail. Hence, we need to conduct further research to find out more about vocabulary mastery, grammar mastery, and writing skill.