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addition, this current study more specifically focuses on the written receptive vocabulary size, that is the number of words required for reading.
g. Words to Count
This question may result more fundamental question about what involves in knowing a word. Another crucial issue related to the question is about what is
included to be in a word. It may involve the issue of the proper noun such as Tim, Davis, or Cathrine to be as a word, or we can also involve foreign word like
perestroika, Latin term, or Sanskrit to be included as a word as well. This should be a decision about the issues of the question as it will affect to the counting of the
word size. However, by referring to the British National Corpus frequency list, the
ideal unit of counting the words is based on the word family. Word family is chosen, rather than the word type or lemma, firstly because research has shown
that word families are psychologically real. Secondly, knowing one members of word family and having control of the most common and regular word-building
process make it possible to work out the meaning of previously unmet member of family Nagy, Anderson, Schommer, Scott Stallman, 1989; Bertram, Laine, and
Virkkala, 2000.
h. Choosing Words to Test
It has been hard to choose the words to test by the teacher. It happens especially in dictionary-based vocabulary size and becomes the major source of
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weaknesses of this method. The source of the problem is that in a dictionary, high frequency words have more entries per word and each entry takes more space than
low-frequency words. If the sample contains too many high frequency words, the learners’ vocabulary size will be overestimated as high-frequency words are more
known than low-frequency words. It does not cover up both high and low frequency words equally.
To select the words to test, there should be some considerations to maintain the balance of the number of low and high frequency words. The teacher
should determine the appropriate words to test and consider the level of difficulty of each word.
i. Receptive and Productive Vocabulary Size
From the studies that had been done by Laufer and Waring, Nation 2001 , it can be found that learners’ receptive vocabulary is greater than their
productive vocabulary size. In addition, the ratio of receptive to productive vocabulary is not constant. Moreover, as learners’ vocabulary increases, the
proportion of receptive vocabulary becomes greater. The gap between receptive and productive vocabulary becomes greater at the lower-frequency levels.
Furthermore, a large portion of the high-frequency vocabulary is known both receptively and productively. The last is that an increase in vocabulary size as
measured by direct measures of vocabulary decontextualised vocabulary test is not necessarily reflected in an increase in vocabulary in use proportion of low
frequency words used in writing a composition.
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j. Types of Language Test
Nation 2011 states that there is a variety of purposes of the language test. The first purpose of the language test is to find out where the learners are
experiencing difficulty so that something can be done about it. It is kind of diagnostic test where the result of the test is used to improve or fix something.
The second purpose is to see whether a recently studied group of words has been learned. It will be best fitted to achieve the result by having short term
achievement test. The third purpose is to see whether a course has been successful in teaching particular words. Unlike the previous objective, this will be best fitted
to achieve the result by having a long term achievement test. The fourth purpose is to see how much vocabulary the learners know. It can be achieved by having
proficiency test done toward the learners. In this current study, proficiency test is the kind of test that will be done to know the estimated vocabulary the learners
know. From the four purposes of the language test proposed by Nation, the last
purpose is what the current study wants to figure out. Through the proficiency test done by the learners, it will result the estimated number of vocabulary the learners
know.
2. Morpheme
Morpheme refers to the smallest, visible unit of semantic content or grammatical function of which words are made up Katamba, 1993. Morpheme
can be categorized into four general classes : free, bound, derivational and
