Research Method RESEARCH METHODOLOGY
A test has to be reliable and valid Hughes; 1989. To see the reliability of the test, the writer used the split-half method. The writer used two scores which
were taken from the odd number and even number. The two sets of scores were used to obtain the reliability of coefficient as if the whole test had been taken
twice. The following formula was used to find out the correlation coefficient r between odd number items and even number items.
Y
Y X
X r
N N
Y X
XY N
xy
2 2
2 2
2
Where, N = the number of subjects
X = the score of odd items Y = the score of even items
Then, by means of the Spearman-Brown formula, the reliability of the test can be estimated.
r r
r
xx
1 2
Where,
r
xx
the estimated reliability of the whole test r
= the Pearson correlation between two halves
A test is said to be valid if it has face validity and content validity. A test is said to have face validity if it looks as if it measures what it is supposed to
measure. Content validity of a test can be seen if its content constitute a representative sample of the language skills Hughes;1989. To construct the test
to have face and content validity, the researcher used the course objective of the English lesson for kindergarten students as the consideration to determine the
material to be tested and the form of the test. In order to see the contributions of the Natural Method to improve the
vocabulary acquisition, the writer used observation check list during the treatment. There was one observer to observe the activities of both classes. The
observer was English teacher. The observer was given explanation about each item in the observation list before observing the class. The observation check list
consisted of a list of items about the occurrence of some activities that improve the vocabulary acquisition during the class activity. The activities were recorded
in term of frequency of occurrence in order to identify more clearly as suggested by Best 1986. The observation check list was as follow:
Frequency of Occurrence Activity
1 2
3 4
5
Where, 1 = never
2 = rarely 3 = occasionally
4 = frequently 5 = always