Final answer:
Job applicants and current incumbents should test the validity of an organization's selection measures to ensure they predict future job performance effectively and are not biased.
Step-by-step explanation:
The individuals of interest to the organization who should test the validity of its selection measures are job applicants and current incumbents. Current incumbents, as 'insiders', have firsthand experience with the job's requirements and can provide valuable insights into what skills and attributes are necessary for success in the role. Testing current incumbents can also help verify that the selection measures are relevant to the actual work being performed. On the other hand, job applicants, as potential 'outsiders', should be subject to the same selection measures to ensure that they possess the necessary knowledge, skills, and abilities (KSAs) to perform well in the job. By involving both groups, an organization can better ensure that selection measures such as IQ tests, skills tests, personality tests, and integrity tests are valid predictors of future job performance and not biased by other factors such as physical attractiveness or negative associations.