Discussion: Ensuring Test Reliability
According to classical test theory, test reliability is based on the notion that test score reliability is comprised of two parts: true scores and error. A true score is an expected score on a test over an infinite number of testing instances; it is a theoretical idea that can never be known for sure. Errors are inaccuracies that make actual (observed) test scores differ from true scores.
There are several different ways to measure a test’s reliability. Test-retest reliability looks at the correlation between original test administrations and re-tests. The span of time between the two administrations should be less that the time for the true scores to vary. Test-retest reliability looks at error due to time.
Alternate-form reliability looks at the correlation between two different versions of a test. Split-half reliability is similar to alternative-form reliability, splitting a single test into two halves—usually odd and even items—and correlating scores on the two halves. Cronbach’s coefficient alpha is also similar, essentially providing the average of all possible split-half reliabilities. Alternate-form, split-half, and Cronbach’s coefficient alpha all look at error due to content sampling.
For this Discussion, select three test reliability methods that could be used in employment test development. Consider advantages and disadvantages of each method.
With these thoughts in mind:
Post a description of the three test reliability methods you chose. Explain advantages and disadvantages of using each method in employment test development. Be specific and provide examples. Support your response using the Learning Resources and the current literature.
- Choose three (3) methods of demonstrating reliability from the various methods of demonstrating reliability covered this week and describe them (using course readings as citations)
- For each of the three methods you choose
- Explain the advantages of the approach for employment testing
- Explain the disadvantages of the approach for employment testing
- Have at least four academic citations in 1 and 2 above, some drawn from the course readings.