Can you help me understand the importance of reliability and validity in psychological assessment and compare and contrast the difference between validity and reliability in standardized testing? Please also give me an example of internal validity, external validity, and reliability. Also, why are they both important in standardized assessment?
Reliability relates to the consistency of a test - specifically, are scores or results consistent across the test itself (for a given individual) and across testing instances (again, for a given individual). Of course, if you're using a standardized test, it's important that it gives you consistent results - if you took an IQ test and got a score of 110 and took it again and got a score of 90, you wouldn't have much faith in the fact that the test tells you anything about how smart you are.
Validity relates to ...
Explains the difference between validity and reliability in research design, giving examples of each.