2 Empirical Validity To determine how test scores are related to some independent, ouside criterion
such as marks given at the end of a course or instructors’ or supervisors’ rating. If the evidence shows that there is a high correlation between test
scores and a trustworthy external criterion, we are justified in putting our confidence in the empirical validity of the test. Empirical validity depends in
the large part on the reliability of both test and criterion measure. 3 Face Validity
It means simply the way the test looks- to the examinees, test administrators, educators and the like. This is not validity in the technical sense and it can
never be permitted to take the place of empirical or content validity. Yet, if the content of the test appear irrelevant, silly or inappropriate, knowledgeable
administrators will hesitate to adopt the test and examinees will lack the proper motivation.
3.10.2 Reliability analysis
To measure reliability of question object used alpha formula as follows:
Formula:
11
r =
⎟ ⎟
⎠ ⎞
⎜ ⎜
⎝ ⎛
− ⎟
⎠ ⎞
⎜ ⎝
⎛ −
∑
2 t
2 i
σ σ
1 1
n n
In which
N N
x x
2 2
2
− =
∑
σ
Explanation:
11
r = the reliability
∑
2 i
σ = the sums of score variants every items
2 t
σ
= total of variant
3.10.3 Level of Difficulties Analysis
Considered from difficulty aspect, the good question is neither too easy nor difficult. The very easy question not reinforce the students to the make their effort
higher in finishing the question. The very difficult question will cause the students give up and don’t have spirit to try again because the question is out of their
ability. The level of difficulties could be measured by the formula:
Explanation: P
: level difficulties of the question
∑
x : The sum of students answer correct
m
S : maximum score
N : The sum of students
m
S N
x P
.
∑
=
Table 3.1
Criteria Interval P
Criteria 0.00 P 0.30 Difficult
0.30 P 0.70 Medium 0.70 P 1.00 Easy
3.10.4 Discriminating Power
The discriminating power will measure how well the test items arranged to identify the differences in the student’s competence.
The formula is :
Where, DP
: The Discriminating Index RU
: The number of students in upper group who answered the item correctly
RL : The number of students in lower group who answered the item
correctly ½ n
: The number of students in one group
n 12
RL -
RU DP
= 33
