The reliability of a subjective test is determined by the degree of its correctness and consistency in providing information regarding the examinee. A reliable test should yield identical results when run multiple times or when used with the same group of students because it is constant in its procedures and criteria. Reliable test results are stable and consistent (McMillan, 2008; Atherton, 2011).
Validity is the ability of a test to measure the intended objective. The three types of validity are content, criterion and construct validity. Content validity is achieved if the content of the test matches the intended objectives. Criterion validity is determined by the capability of the test to relate to other external factors. Construct validity considers educational variables while predicting the test results (McMillan, 2008).An example of an objective test is:
The reliability of a subjective test can be measured by giving the same test more than once or giving creating two forms of the same test with slight variations. The reliability of such test is measured by calculating the correlation of the consistency. Internal consistency is determined by correlating a half of the assessment with the remaining half. Reliability consistence ranges from 0 to 1.0 with 0 representing absence of reliability while 1 depicts perfect reliability. Test with a reliability coefficient of above 0.8 are considered to be standard while those with a coefficient below 0.5 are considered to be less reliable. Validity is measured by establishing if the test meets or measures the intended objective (McMillan, 2008; Atherton, 2011).
Determining the reliability and validity of a test is important since it help in establishing accuracy of the grade obtained using such a test, if a test is valid and reliable the results obtained are considered a true depiction of the students’ level of understanding
Formative assessment is used by the teachers or lecturers to obtain