c Split-Half Method
In this procedure, the test is just given once to a group of subjects or at one time. Those items are divided into two sections
that are comparable, usually by differentiating the question to even and odd numbers. The result of each section of question was
checked, then the scores of the two sections correlated to find the correlation of coefficient. The correlation applies only partially, not
for the entire question, but only for half. split half formula, as follows:
R
tt =
Notes : r
tt
= coefficient reliability of a test
r
gg
= even and odd correlation coefficient half the test with
otherhalf Karno, 2003:10
d Rational Similarity
This procedure is done by combining each item in the test with other items of the as a whole.
3. Level of Difficulty
Good question is a question that is not too hard and not too easy. In other words, the degree of difficulty of the test is enough Suharsimi
Arikunto, 2013: 223. Numbers that show the difficult and easy questions are called index of difficulty. Index of item difficulty is a number that
shows the difficult and easy questions. The higher the index, the easier
item difficulty. The level of difficulty analysis of questions is done to examine the issues in terms of the difficulty to obtain the questions which
include hard, medium, and easy. According to Witheringthon in Anas Sudijono 2011: 371 and
Suharsimi 2013: 223 index of item difficulty number is 0.00 to 1.00. The greater the difficulty, the easier index number of problem. If all
the examinees answered with one of these items, the matter is very difficult to the difficulty levels of 0.00 and if the difficulty level is 1.00, it
is very easy because answered correctly by all candidates. The test consists of two forms of the test is an objective test and
essay test, then in calculating the level of difficulty is used in different ways. To test the form of an objective in calculating the level of
difficulty, can be done by using the following formula:
Notes: P
= index of difficulty
B =
the number of students who answered the question correctly
JS =
the total number of student who participated in test Suharsimi, 2013: 223
The criteria of difficulty index of questions are as follows: 1,00 0,71 = easy category of question
0,31 – 0,70 = medium category of question
0,00 0,30 = hard category of question Suharsimi, 2013: 225
To calculate the level of difficulty of the test in form of essay according to Anas Sudijono 2011: 134 must be done the steps as
follows: a
Calculate the average score for each item with the formula:
b Calculate the level of difficulty using the formula:
c Compare the level of difficulty with hardship criteria
d Make interpretation of difficulty level by comparing coefficients
with the difficulty level criteria.
4. Distinguishing Power
