Use achievement tests to pick out those applicants who already possess a special skill or knowledge needed to perform a job. As opposed to aptitude tests, which assess an applicant's potential, the achievement test determines what the applicant already knows. So, achievement tests are usually the most reliable and valid at predicting job performances.

What type of achievement test should you use? Some achievement tests are actually performances — an applicant is given a letter to be typed or a forklift to be driven. Typing, knowledge of a word processing program, and other clerical tests are, in fact, the most widely used employment tests because they are demonstrably job-related. We suggest that you strongly consider using a simple performance test by giving an applicant a task that would be commonly required on the job and seeing how he or she does.

Another type of achievement test might be one that puts the applicants in a hypothetical situation to gauge their responses.

You want to hire someone for customer service purposes. You might ask the applicant to get on a phone in an office and call him or her from a phone in the next room and pretend to be an angry customer to see how the person reacts.