Validity is a measure of how well a test measures what it claims to measure. Psychological assessment is an important part of both experimental research and clinical treatment. Reliability refers to the consistency of the results in research. ... Reliability is highly important for psychological research. This is because it tests if the study fulfills its predicted aims and hypothesis and also ensures that the results are due to the study and not any possible extraneous variables Reliability addresses the overall consistency of a research study's measure. ... A research study design that meets standards for validity and reliability produces results that are both accurate (validity) and consistent (reliability).