47 particular time. The advantage of using this design is that it is able to measure
current attitudes or practice yet the survey and data collection can be administered in short period of time. It means that this cross-sectional study is time efficient.
Borg and Gall 1983 agrees that in a cross-sectional study the data can be gathered in a single point in time and the data gathering can be carried out in a
short period of time. As the population of this study is the students of English Letters Department that requires its students to finish the study in four years or
eight years in average, consequently, conducting a longitudinal study on this subject will need at least four years or eight semesters. Therefore, in order to do
the research efficiently, in the term of time, the researcher decided to use cross- sectional study in order to accommodate the objectives of this study.
B. NATURE OF DATA
The data-gathering instrument of this study is in a form of a written test. The obtained data from the written test result is in a form of test scores. The
scores from the test result are categorized as interval data for its equal difference between each value. Cohen et al. 2000 state that interval data use a ratio scale
that contains absolute zero with equal intervals between each value. The interval data used in this study was obtained from test result scores of 90 students from
three different English proficiency levels, a detailed table of this test score result is presented in Appendix 3. A group of students represented each proficiency
level; in this case, each group of students consisted of 30 students. The scores were divided into two main groups: the score of grammatical aspect usage and the
score of grammatical aspects knowledge. Each group consisted of four groups of scores: score of simple aspect, perfect aspect, progressive aspect and perfect-
48 progressive aspect. Further, the data obtained were analyzed with IBM SPSS
software.
C. RESEARCH POPULATION AND SAMPLE
In a conducting a research, selecting the suitable samples is important. Johnson 1992 argues that ‘the way the sample is selected affects the conclusion
that can be drawn about the result.” When conducting a research with a large- scale population it is necessary to select a sample to make an estimation of the
whole population characteristics. Moreover, sampling is beneficial for the researcher in the terms of time and cost efficiency Kish 1965, Gupta and Kapoor
1970 as cited in Singh and Masuku, 2014. Related to the significance of sampling, Cohen et al. 2000 agree that
instead of methodology and instrumentation, the research quality is determined by the appropriateness of the selected sampling strategy. Cohen et al. also highlight
four significant factors in sampling: “1 the sample size, 2 the representativeness and parameters of the sample, 3 access to the sample, 4 the sampling strategy to
be used.” Hence, based on those points then in obtaining the research samples, the writer decided to adopt probability sampling particularly the cluster-sampling
strategy. Probability sampling draws the sample randomly from a wider population
scale; it aimed at finding representatives of the population to draw a generalization. In contrast to probability sampling, non-probability sampling takes
representation from a more particular group of the population instead of a wider population scale Cohen et al. 2000. A cluster-sampling strategy was selected
considering the large number of population that needs to be investigated. In the
49 cluster-sampling strategy, the population is divided into clusters and the members
of each cluster must be homogeneous. Each cluster is randomly selected from the total population. Neuman 2007 adds that in the cluster sampling a cluster is
considered as a unit in which there is the sampling elements nevertheless, the sampling element can be treated as a sampling itself.
The population of this study is students of English Letters Department of Sanata Dharma University. This study program requires its students to complete
the study in four years or eight semesters. In this cross-sectional study, the writer decided to select three groups of students from the second, the fourth and the sixth
semester students to take a representative sample from three different language proficiencies. The second, the fourth and the sixth semester students represent the
freshman, sophomore and the junior students respectively. The sample consists of three clusters or groups of students: the second semester, fourth semester and the
sixth semester students of English Letters Department of Sanata Dharma University. Each group was represented by a group of students consisted of 30
students. Therefore, there were total 90 students as the samples of this study.
D. DATA GATHERING TECHNIQUES AND INSTRUMENTS
To obtain required data that will be analyzed in this study, the researcher needed to use instruments or tools. There are many types of data gathering
instruments that can be utilized to obtain data. Cohen et al. 2000 recommend nine types of data gathering instrument to obtain data for research in education:
interview, questionnaire, observation, test, accounts, biographies, and case studies, role playing, stimulations and personal construct. In determining the most
appropriate research instrument, one should consider about what kind of research
