Results are often reported as a total score, but there is additional information in individual items of tests which vary in their difficulty and discriminatory value.
We operationalized test difficulty as the average facility index of the items of the test – the proportion of students that sat the test that answered the question correctly.
Under the classical test theory, the teacher's test score is the sum of the scores received on the items of the test.
The items of the test used in this paper were self-developed by the researcher.
A person's ability can thus be estimated by the number of the items of the test the person has solved correctly (i.e., the sum score).
The model assumes local stochastic independence and thus one-dimensionality, which means that all items of a test measure the same underlying construct.
It further demands subgroup homogeneity, which means that all items of a test measure the same underlying construct across different subgroups (e.g., girls and boys).
The 88 items of the test assess activities in five dimensions.
Descriptive statistics were used to summarize demographic characteristics and scores on items of the test.
