Domestic and international competition has affected the operations of virtually all organizations.  Such competition has demanded that organizations do everything possible to eliminate or reduce inefficiency and improve production methods.  Those activities require a high quality, skilled workforce.  It is through selection decisions, made one at a time, that an organization creates the basis for this skilled workforce.  In many cases, there are more applicants for a job than there are available openings.  The organization must, therefore, determine who to hire.  Personnel selection is the process of collecting and evaluating information about the group of applicants for a particular job opening, which is used in making decisions about to which applicant(s) an offer of employment should be extended. 

The basic premise of any selection program suggests that from among a group of applicants some subset is more likely to possess the skills and abilities needed to perform the job.  The purpose behind any selection procedure is, therefore, to improve the prediction of which applicants are more then less likely to perform successfully on the job.  This prediction is made based upon information gathered regarding applicant knowledge, skills, abilities and other characteristics (KSAs).  As such, high quality selection is one method by which I/O psychologists working in organizations can impact the bottom line. To improve the likelihood that predictions will be accurate, the information gathered about each applicant must be of high quality and there must be some evidence that the information collected is relevant to job performance. Selection decisions made based upon high quality information make good business sense.  They help to ensure that work is being done by employees who have the skills and abilities required to perform job functions.  Lower quality selection decisions reduce the likelihood that the predicted performance will meet expectation.  Applicants rejected because they lack KSAs unrelated to job performance may prove to be effective employees.

In addition to the benefits relevant to bottom line results, selection programs have other benefits for both the organization and the individual.  Making decisions about selection based upon job relevant predictors of performance ensures that decisions are based upon fair criteria and not on irrelevant factors such as race, sex, religion, age, etc.   In addition, decisions made based upon relevant information help ensure that those individuals who are eventually hired into the position are less likely to end up in jobs for which they are ill-suited and, therefore, likely to fail and/or to experience job-related stress due to the poor match between their particular skill set and the jobs requirements. 

The next section discusses the quality of measurement taken or information gathered in selection processes.