According to Wortman (2011), validity means the degree, to which a test or an assessment can take up measurements. It is usually obtained by comparing and contrasting the outcomes or the scores of various pupils with some stated construct and criterion. According to the Board of Children, Youth and Families (2008), validity is the evidence used to support any assessment assignment. It helps in finding out whether an assessment has achieved the intended purpose. Citing example, Wortman (2011) maintains that if used children’s’ assessments, the study should be designed in such a way that ensures accuracy. This may involve a series of tests to ensure more trustworthy and accurate, valid assumptions.
On the other hand, Wortman (2011) defines reliability as the consistency, with which the various assessments obtain or produce similar results if in similar conditions. He argues that any assessment, aiming at obtaining the reliability, must be continually compared to the earlier ones to determine whether the information being obtained from the assessment is consistent or not. Reliability is, therefore, important in ascertaining the level of consistency of any given study. Just as is the case with validity, it is ascertained by conducting repeated assessments over the same tests at different time frames.
Finally, Wortman (2011) notes that it is never possible for any assessment to be valid if it is not reliable in the first place. That means, a test cannot measure as intended if it is producing varying results upon several trials. He also argues that being reliable does not also not mean that a test is obviously valid since there can be a mistake or human errors that are common to a number of scientists. Such errors can result from the human nature or defects in the technologies which are being used.
In conclusion, validity and reliability are very important tools for any particular research process. It is, therefore, good for scientists to familiarize themselves with the two concepts because of their high interrelation that may make them be confusing and thus impact negatively on the interpretation of the research results.