Reliability and Validity
What is test stability? Explain why it is important to verify stability of a test instrument
Test stability is the capacity of an instrument concerning the production of similar results when the instrument is used repeatedly (In LoBiondo-Wood, and In Haber, 2014). This could be interpreted as consistency becoming stability because the instrument used in the study proves to be consistent over time. Critical to the discussion is the reality that test stability is important when conducting longitudinal and intervention studies because the latter studies are meant to effect specific changes while the former studies measure the same element repeatedly.
Explain parallel form test reliability, and give an example of how parallel form tests are verified.
Parallel form test reliability is used to examine the reliability of a test using say, different sets of questions that measure the same variable or concept. Simply put, two different tests are used to measure the same element almost immediately. It is notable that parallel form test reliability is verified by obtaining the correlation coefficient from the two sets of results. This implies that parallel form test reliability is confirmed after a high correlation is obtained from the results (In LoBiondo-Wood, and In Haber, 2014).
Explain test-retest reliability. Give an example of how test-retest form tests are verified.
Test-retest reliability is used to confirm that the results of a study are reliable by testing the same subjects using the same instrument and under similar conditions more than once. Such tests are verified using the Pearson correlation coefficient. This implies that the presence of a high correlation coefficient indicates the presence of reliability when the test-retest reliability is used (In LoBiondo-Wood, and In Haber, 2014).
What is test validity? Give an example.
Validity is concerned with the accuracy of the measuring instrument on the variables being collected (In LoBiondo-Wood, and In Haber, 2014). For example, when measuring the IQ of study subjects the instrument used should not only measure IQ accurately, but also measure IQ and not the cramming power of the study subjects.
Why is test validity important?
Test validity is important owing to the fact that it increases the audiences’ and researcher’s confidence in the findings of the study (In LoBiondo-Wood, and In Haber, 2014).
Reference
In LoBiondo-Wood, G., and In Haber, J. (2014). Nursing research: Methods and Critical
Appraisal for Evidence-based Practice. St. Louis, Missouri : Elsevier