According to the Public Service Commission of Canada, research shows that unstructured interviews can lead to poor hiring decisions because they are more vulnerable to:
Bias and Inequity
People are often unaware of their own biases and how these biases unconsciously influence their decisions. Research shows that attributes such as physical attractiveness, a similarity of the applicant to the interviewer, gender and race can inappropriately influence an interview panel’s assessment. Personal beliefs and values may also influence the unstructured interview process so that different questions may be asked of different people, or the same answer provided by different applicants may be interpreted differently.
Inaccuracy and Low Prediction
Studies show that unstructured interviews are relatively ineffective at predicting job performance. This finding is largely attributed to the use of questions that are not necessarily based on qualifications required to perform the work. Since the assessment criteria are unclear, interview panel members may inaccurately and inadvertently judge applicants on irrelevant factors. Also, unstructured interviews make it easier for applicants to give answers they think the interview panel is looking for, rather than answers that provide accurate information on how they will perform once on the job.
Legal Vulnerability
Unstructured interviews are more likely than structured ones to be challenged in court, based on grounds of illegal discrimination. A review of 158 United States federal court cases involving hiring discrimination from 1978 to 1997 revealed that unstructured interviews were challenged in court more often than any other type of selection device. Even more important is an examination of the outcomes of such legal challenges. Unstructured interviews were found to be discriminatory in 59% of these cases, whereas structured interviews were found to be discriminatory in 0% of cases.