Interviewing is one of the most important steps in the lifecycle of an employee. The average bad hiring decision can cost an organization approximately 30 percent of the bad hire's first-year earnings, according to the U.S. Department of Labor. Not to mention the psychological costs that a bad hire can have on a team's culture.

So, how do leaders go about conducting a proper interview?

Luckily, there is more than 85 years of research in behavioral science and organizational psychology that provides an evidence-based and definitive answer to this question. This research is based on thousands of studies performed with millions of employees, which has yielded the most effective interview techniques.

There are three components to know and apply: general mental ability tests, work sample tests, and structured interviews.

General Mental Ability Tests

Tests of general mental ability measure multiple specific abilities (e.g., verbal, numerical, spatial). Examples of these tests include the Wonderlic Personnel Test, Otis Employment Test, and Raven's Progressive Matrices Test. In contrast to assessments that measure knowledge specific to a particular job, general mental ability tests are relevant for hiring across occupations and roles (e.g., managerial, clerical, services, sales, trades, and crafts).

General mental ability tests are an especially useful tool because they facilitate objective comparisons against applicants and save the organization precious resources (e.g., do not require an HR official to administer). 

When employing general mental ability tests in the recruitment and selection process, consider the following:

  • If not designed carefully, general mental ability tests are vulnerable to racial, ethnic, and cultural differences, posing a risk of unfairly discriminating against applicants from underrepresented backgrounds. These tests are a useful tool to predict future performance but hiring decisions should not be based solely on results from these tests.
  • Be transparent with job applicants. Inform applicants of the purpose of the test, how the results will impact hiring decisions, and how the organization will use the results after the hiring decision has been made. If job applicants feel the test is administered in a manner that violates their perceptions of fairness, then the test may cause them to lose interest in joining the organization.
  • Some applicants encounter test anxiety when taking general mental ability tests. To counteract anxiety, try to gamify the test. If you can make the test feel more like a game, applicants may experience it as fun instead of an anxiety-provoking exam. 

Work Sample Tests

Work sample tests are hands-on simulations of work that are physically and/or psychologically similar to the actual work performed on the job. Employers administer work sample tests to one applicant at a time, which allows employers to judge the applicant's skills and expertise. In this way, work sample tests are costly to administer yet difficult for applicants to fake their performance.

For example, as part of a work sample test, an applicant for a handyman role might be required to repair a broken item, while an applicant for an engineering role might be required to write lines of code.

When employing work sample tests in the recruitment and selection process, consider the following:

  • Fairness is an important principle when designing and scoring work sample tests. Consider reducing bias by treating all applicants the same way, including the amount of time to complete the test, and score the test following a rubric which blinds the applicant's name and personal information (e.g., gender, age, race/ethnicity).
  • Work sample tests capture an applicant's existing knowledge and expertise but do not capture an applicant's ability to learn new material on the job. In this way, work sample tests might not be suitable for applicants who lack professional expertise.
  • Remember that the purpose of a work sample test is to evaluate an applicant, not to have an applicant produce work that is repurposed to benefit the company. Applicants are not paid to submit a work sample test, and thus the work that they produce should not be used without their permission in the future.

Structured Employment Interviews

There are two types of interviews: structured and unstructured. While structured interviews have a fixed format, an established set of questions to be answered, and a predetermined procedure for scoring responses, unstructured interviews lack a fixed format, an established set of questions, and a procedure for scoring responses. Structured -- but not unstructured -- interviews are a useful tool for predicting job performance.

If carefully implemented, structured interviews ensure that two interviewers -- who independently interview the same applicant -- will come away from the interview with a similar score for the applicant.

When employing structured interviews in the recruitment and selection process, consider the following:

  • The questions asked during the structured interview should be tailored to the specific job. Each job is different and thus requires unique knowledge, skills, and abilities.
  • The questions should not be solely developed by the manager. This is because the manager often does not have direct experience doing the job, and thus lacks accurate and complete information as to the knowledge, skills, and abilities needed. Instead, consult with subject matter experts (e.g., those who have experience doing the job) about what is truly required to perform the job effectively.
  • The scoring rubric for each question should be described in terms of observable behaviors. A rubric that is grounded in terms of observable behaviors will produce more consensus across multiple interviewers, as the more observable a behavior is, the more that it can be "seen" by multiple interviewers. In contrast to observable behaviors, impressions are inherently subjective, making it more challenging for multiple interviewers to agree on a score. 

Good interviewing is an art as well as science. General mental ability tests, work sample tests, and structured interviews are techniques that should be in every HR's toolkit, while less effective methods -- such as personality tests, reference checks, and interest surveys -- should be avoided.