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

This research is aimed to get emperical data and analyze the effects of vocabulary and grammar mastery on writing skill in descriptive text at private junior high schools in Serang Banten. This research is done by Kolmogorov-Smirnov method, ANOVA Table, Proportional Correct for testing the item difficulties, by biserial coefficient, and by Kuder Richarsson testing. The research was held at Privates Junior High Schools in Serang Banten. Data collective done by giving test for writing skill (make a composition or an essay about an object description), test for vocabulary mastery (multiplechoice/ 35 items), and test for grammar mastery (multiplechoice/ 35 items) given to class at MTs Al Ma’arif, MTs Nurul Basmallah and MTs Nurul Huda. The result of study identifies there are effects between Vocabulary and Grammar Mastery towards Student’s Writing Skill in Descriptive Text (Fo = 18.748 and Sig = 0,000 < 0,05; coefficient of 0.666 and the coefficient determination of 81.5%). There is effect of Vocabulary Mastery towards Student’s Writing Skill in Descriptive Text (Sig = 0.026 < 0,05 and ttest = 2,301; while ttable = 1,88). There is effect of Grammar Mastery towards writing skill in Descriptive Text (Sig = 0.002 < 0,05 and ttest = 3,656 while ttable = 1,88).

statement of (Oshima et al., 2007) Writing is an iterative process, a process of revision and rewriting. Writing is by no means a one-step action. It's a continuous creative act. Writing is not a one-step action and must be continuous and repeated in order to get good and quality results. (Swan, 2005) defines that a grammar shows how words are combined, arranged, or modified to reveal a particular meaning. (Coghill & Magedanz, 2003) moreover states that the grammar of a language is a set of rules that determine its structure. Grammar determines how words are arranged to form meaningful units. Based on the explanations, the researchers conclude that grammar is an important thing for students to arrange the sentences. Therefore, these rules are not always consciously understood, as the rules we refer to are rules that almost no one thinks of, but in most cases people can easily make their language easier. And I want to be able to use it naturally. Grammar is a rule of how to combine words and their components into sentences.
This research is aimed to get empirical data and analyse the effects of vocabulary and grammar mastery on writing skill in descriptive text at private junior high schools in Serang, Banten, West Java, Indonesia

Method
This study emphasizes on the effect of English vocabulary and grammar mastery towards student's writing descriptive text. The researcher used a survey with an analysis of the regression as the method in this research. Whereas the data and information in this research will be taken by questionnaire and test.
Therefore, this survey is clearly visible throughout the survey design in the following figure. : Grammar mastery as independent variable Y : Student's writing descriptive text as dependent variable Sugiyono (Sugiyono, 2013) states that this population is an area of generalization consisting of: Objects or subjects with specific qualities and characteristics are determined by the researcher under investigation and conclusions are drawn from them.
The object of the research class VIII, the total numbers of students from the three schools are being surveyed 50 students.

Research Instrument
The data will be collected by giving 1 kind of objective test for independent variables, and a set of written test for dependent variable. Both written test and objective test are given to 50 students from 3 schools, which are set as samples. For the tests in multiple-choice forms are vocabulary mastery and grammar mastery. For vocabulary mastery and grammar mastery the respondents are tested in 35 problems with four option (A,B,C, and D), and written test for descriptive test. The results of the effects of vocabulary mastery and grammar mastery towards student's writing skill in descriptive text are analyzed with to (tobserved) in significance grade 5% (α =0,05) and degree of freedom (df) = n-2.
Data collection is done by distributing questionnaires to respondents so that data can be taken. Furthermore, it is data analysis vocabulary mastery done by studying the instrument which is suitable analyzed by data analysis vocabulary mastery, as follows:

Normality Test
Normality test is used to determine whether the data in this research is normal or not. Testing normality of the sample should be done by Liliefors test with the determination Lobsevered < Ltable. If this term is fulfilled, then the data is derived from normal population. With F value (Zi) is guided by the distribution of normal standard, then will be calculated the value of F probability (Zi) = P (Z < Zi) Lobserved is obtained from the biggest value of total decrease between F (Zi) and S value. Ltable is obtained from Liliefors table. The result of research data is normal distribution if the value of Lobserved < Ltable on significant level of 0.05.

Hypothesis Test
The collective data is modified into interval data and then analyzed by SPSS 20.0. As for the purpose of hypothesis test, the analysis measurement taken is multiple regressions. Thus, it will be found that how big the influence of both independent variables (Vocabulary Mastery and Grammar Mastery) towards dependent variable (Students'skill in writing descriptive text), both individually and jointly.

Results
Researchers tried to understand the distribution of data obtained from the study results and comparing the distribution of data obtained from the results of research conducted to be calculated. We performed a descriptive data analysis to find the data range, mean, median, mean, and standard deviation. These data represent statistical descriptions from the results of calculations and tests performed by the computer application program SPSS 20, as well as their analysis and interpretation.

The Data Analysis of Vocabulary Mastery (X1)
A vocabulary score of from 50 respondents shows an average of 54.30, a standard deviation of 8.430, a median of 53.50, a minimum score of 33, and a maximum score of 70. There were 35 questions given as the instrument for vocabulary mastery. Based on statistics table above, student's vocabulary mastery are categorically low. Compared to the minimum completeness criteria based on the curriculum for English is 70, it shows that the average score was below criteria based on the curriculum. Students's score above 70 are only 3 students from 50 respondents. Next, based on the minimum score, there were 4 students (2.8%) who could answer 14 questions from 35 questions given. It was indeed the score very low. The score for standard deviation is 8.430 or quite the same with 15.52% from the average. It shows that different answers between respondents were in the middle level. It also shows that the data score of vocabulary mastery of the respondents are various. From the description, it can be seen that between the average score and the median are almost the same, they are 54.50 and 53.50. It shows that the data score of vocabulary mastery from this research is quite representative. In order to describe the existing data range clearly of the students' vocabulary mastery variable

The Data Analysis of Grammar Mastery Variable (X2)
The score of Vocabulary Mastery which was obtained from 50 respondents shows the average is 54.66 with the standard deviation of 9.271, median of 54.00, minimum score of 33 and maximum score 72. There were 35 questions given as the instrument for grammar mastery. Based on the above data, student's grammar mastery are categorically low. Compared to the minimum completeness criteria based on the curriculum for English is 70, it shows that the average score was below criteria based on the curriculum. Students's score above 70 are only 9 students from 50 respondents. Next, based on the minimum score, there were 5 students (7.2%) who could answer 14 questions from 35 questions given. It was indeed the score very low. The score for standard deviation is 9.271 or quite the same with 16.96% from the average. It shows that different answers between respondents were in the middle level. From the description, it can be seen that between the average score and the median are almost the same, they are 54.66 and 54.00. It shows that the data score of grammar mastery from

The Relation of Regression Line Linearity between Variable X1 and Variable Y
The result calculation of the relation of regression line linearity test between variable X1 and variable Y can be seen in Table 4.3. From the table 4 above, it shown that the score in column Sig line Deviation from Linearity (0.625) is more than 0.05 (>0.05), so that H0 is accepted, in other words that the regression line between variable X1 and variable Y is linear. In other words, the equation of regression line between vocabulary mastery and students' writing skill in descriptive text forms linear pattern. It means, that the better of the student's ability of vocabulary mastery, the ability of writing skill in descriptive text is good as well.

The Linearity of Regression Line, the Relation between Variable X2 and Variable Y
The result of regression line linearity test, the relation between variable X2 and variable Y can be seen in Table below ANOVA Table  Model Sum The above table is shown that the score in the column Sig line Deviation from Linearity (0,877) is more than 0.05 (>0.05), so that H0 is accepted. In other words, that the regression line between variable X2 and variable Y is linear. In other words, the equation of the regression line between student's grammar mastery and the student's writing skill in descriptive text forms the linear pattern. In other words, the better students' grammar mastery, the ability of writing skills in descriptive text good as well.
Test of hypothesis was carried out with the purpose of answering the formulation of the problems which has been determined after research data has met the requirement. Based on what was written at the end of Chapter III, test of hypothesis carried out with the intention to answer formulation of the problem

Conclusion
Based on the results of the discussion, it can be concluded that writing skills are influenced by vocabulary and grammar. It can be shown that there are significant effects of vocabulary and grammar mastery jointly on student's writing skill in descriptive text at private junior high schools in Serang Banten. It is proved by the value of Sig 0,000 < 0,05 and Fobserved =18.748, Also, there is significant effect of vocabulary mastery on student's writing skill in descriptive text. It is proved by the value of Sig 0,026 < 0,05 and tobserved = 2.301 and there is significant effect of grammar mastery on student's writing skill in descriptive text. It is proved by the value of Sig 0,001 < 0,05 and tobserved = 3.656. it means that teachers must provide more knowledges related to writing English and assist them in writing learning process.