Reliability-does the test yield the same or similar score rankings (all of the other factors being equal) consistently?
by Darcia Watson
1. Test-Retest or Stability-test is given twice and the correlation between the two scores are determined.
2. Alternate Forms or Equivalence-if there are two equivalent forms of a test, these forms can be used to obtain an estimate of the reliability of scores.
3. Internal Consistency-Assume that people who get one item right will get other right. Divide questions to different parts of test. Split-half methods-(odd-even) put half in each part of test, then total score for each student on each half is determined and the correlation between the 2 scores is calculated.
4. Kuber-Richardson Methods-calculate the percentage of students passing each item on the test.
5. Why important? It is important for a test to come up with the same or similar scores, because if it does not it cannot be used to determine ranking, placement etc.. The information needs to be stable, consistent, and dependable.
