Validity

The headless professor defines validity and how it is established by way of a 2 x 2 contingency table. He also discusses different types of validity such that in clinical psychology (diagnosis and prognosis) and industrial/organizational psychology (performance). Define validity in your own words.


Why is it important to establish validity in clinical psychology and industrial/organizational psychology? Why did the headless professor present the 2 x 2 table to explain validity?