Reliability, Validity and Norming Sample Populations Play

Reliability, validity and norming sample populations play critical roles in the usefulness of assessment instruments used in forensics assessments. These three facets of assessment help to determine whether or not the results the assessment yield is credible. Additionally, they each help to evaluate a particular aspect of an instrument, although there is generally a degree of correlation between these factors.

Validity is simply the accuracy of a test to effectively measure the particular phenomenon that a researcher is attempting to measure. There are different types of validity including construct validity, content validity, and criterion-related validity (Richmond, 2013). These different facets of validity determine the accuracy of an assessment in terms of its construct, its usefulness is appropriately sampling the different components of the construct, and its accuracy in foretelling performance. Reliability is the facet of an assessment to provide consistency in its results over time. Reliable tests can generally yield the same results regardless of when an assessment is taken. It is important to realize that "without reliability, there can be no validity" (Richmond, 2013). Norming sample populations help to provide a way of measuring results of a particular sample against one that is considered normal. Norms provide statistical information of the results of a test for an average population setting that is well-defined. In this instance, well-defined is used as a term that means a stratified sample population that is categorized according to various elements of a construct that a forensics assessment is examining.

Each of these facets of forensic assessment are extremely important when completing testing in this field. For instance, if a researcher was using an instrument to assess proclivity for future violence, it is important to use an instrument which tests this particular construct. A personality test might apply to the researchers needs; however, another instrument such as an IQ test would not. It is worth mentioning that there are forensic instruments more specific to violent tendencies than either of the aforementioned ones.

The reliability of an instrument used to determine future violence is extremely important, since the consequences of the results of such an instrument could play a major factor in the future of the subject. For instance, such an instrument might be used to evaluate in what sort of prison someone convicted of a crime is placed. Or, perhaps even more saliently, the results of such an instrument might pertain to whether or not an incarcerated individual is eligible for parole. Similarly, the importance of the norming sample population is critical in such a test, because it is used to determine whether or not the specific results of a particular subject warrant him or her as at-risk for future violence, or not.