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Virtually every organisation relies on interviews to make employee selection decisions, and yet a tiny portion of those organisation actually know how best to interview candidates. Hiring decisions made using interviews have far-reaching implications on productivity, employee engagement, and company culture, perhaps more so than any other decisions made by that organisation.

Consequently, it is essential for organizations to adopt effective and unbiased methods for evaluating job candidates. One such method is the structured interview, which has been shown to significantly outperform unstructured interviews in both reliability and validity.

In this article, we will explore the key differences between structured and unstructured interviews, discuss the psychometric advantages of structured interviews, and highlight their role in mitigating bias and identifying top talent.

section one

Structured vs Unstructured Interviews

In order to fully appreciate the benefits of structured interviews, it is essential to distinguish between structured and unstructured interview formats. While both methods serve the purpose of assessing candidates for employment, they differ significantly in their approach, effectiveness, and susceptibility to bias. Understanding these key differences can enable organizations to make informed decisions when designing their interview processes.

Structured interviews involve a predetermined set of questions and a standardized evaluation criteria that are consistently applied to all candidates. This systematic approach is based on the premise that by providing a uniform and objective framework, interviewers can effectively compare candidates' responses, evaluate their qualifications, and make evidence-based hiring decisions. Research has consistently shown that structured interviews are more reliable and valid predictors of job performance than their unstructured counterparts.

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If you would prefer to watch a video, here is Ben Schwencke talking about the advantages of structured interviews (as opposed to unstructured ones):

On the other hand, unstructured interviews are characterized by a more casual and free-flowing conversation between the interviewer and the candidate. The questions asked in unstructured interviews are typically not pre-established and can vary greatly between candidates. While this approach may foster a more natural interaction and reveal personal insights, it is inherently subjective and prone to bias. The lack of standardization and consistency in unstructured interviews can lead to unfair comparisons and poor hiring decisions, often influenced by the interviewer's personal beliefs or unconscious biases.

"Overall, there are three key reasons why employing organizations should never rely on unstructured interviews for employee selection and instead utilize structured interviews for assessment."

Although structured interviewing makes intuitive sense, the vast majority of interviews are unstructured and conversational, for many reasons. Firstly, few managers actually receive any formal training in interview practice and are simply unaware of the downsides of unstructured interviews. Secondly, even among those offering training, the academic research behind structured interviews is not well-known, and thus few people hear about the advances of structured interviews. Lastly, many managers simply shrug off the ineffectiveness of unstructured interviews, believing themselves to be usually effective interviewers and thus do not need a structured interview format.

section two

Psychometric Reliability of Structured Interviews

From a psychometric perspective, structured interviews are more reliable than unstructured interviews due to several key factors: standardization, objectivity, and the ability to accurately measure job-relevant competencies. These factors contribute to the overall validity of structured interviews, making them a more effective tool for identifying top talent.

  • 1. Standardization: One of the primary reasons structured interviews are more reliable is their standardization. In this format, all candidates are asked the same predetermined questions in the same order, ensuring that the interview process is consistent across all applicants. This uniformity minimizes extraneous variables that could potentially influence the interview outcomes and allows for a fair comparison of candidate responses. As a result, structured interviews provide a stable and consistent measure of candidate performance, which is essential for establishing reliability.
  • 2. Objectivity: Another key factor contributing to the reliability of structured interviews is their objectivity. By employing a standardized scoring system or rubric for evaluating candidate responses, structured interviews minimize subjective judgments and reduce the potential influence of personal biases. This objectivity enhances the reliability of the interview process, as it ensures that candidate evaluations are based on consistent and relevant criteria. Moreover, the use of objective scoring criteria makes it easier for multiple interviewers to reach a consensus on candidate evaluations, further bolstering the reliability of structured interviews.
  • 3. Job-Relevant Competencies: Structured interviews are designed to measure specific job-related competencies that have been identified as critical for success in the position. By focusing on these competencies, structured interviews are more likely to accurately capture the skills, knowledge, and abilities required for the job. This targeted approach ensures that the interview questions are relevant and aligned with the job requirements, which contributes to the overall validity and reliability of the structured interview process.

In contrast, unstructured interviews often lack a clear focus on job-relevant competencies, leading to less reliable and valid evaluations. Without a systematic approach to measuring the essential skills and abilities for the role, unstructured interviews can be influenced by factors unrelated to job performance, such as personal preferences or unconscious biases. This reduces the psychometric reliability of the unstructured interview, adding unwanted error into the assessment.

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section three

Psychometric Validity of Structured Interviews

In addition to being more reliable, structured interviews also boast higher validity from a psychometric perspective. Validity, the degree to which an assessment tool measures what it intends to measure, is crucial in the hiring process to ensure that the most suitable candidates are selected. Structured interviews outperform unstructured interviews in terms of validity for several reasons: criterion-related validity, construct validity, and reduced susceptibility to bias.

  • 1. Criterion-related Validity: Structured interviews demonstrate stronger criterion-related validity, meaning that they are more effective in predicting job performance. By using standardized questions that focus on job-relevant competencies, structured interviews assess candidates' knowledge, skills, and abilities directly related to the position. Consequently, the scores obtained in structured interviews have been found to correlate more strongly with actual job performance, making them a more valid predictor of future success in the role.
  • 2. Construct Validity: Another aspect of validity is construct validity, which refers to the accuracy with which a test measures a particular theoretical construct, such as problem-solving or leadership skills. Structured interviews excel in this regard by targeting specific constructs that have been identified as essential for success in the job. This focus ensures that interview questions are aligned with the intended constructs, leading to more accurate and valid assessments of candidates' abilities. In contrast, unstructured interviews often lack a clear connection between the questions asked and the constructs they are meant to assess, diminishing their construct validity.
  • 3. Content Validity: The last aspect contributing to the validity of structured interviews is content validity, which refers to the degree to which an assessment tool represents all facets of the domain it is intended to measure. In structured interviews, questions are carefully developed based on a thorough job analysis, ensuring that they cover a comprehensive range of skills, knowledge, and abilities required for the position. This comprehensive coverage ensures that structured interviews provide a representative sample of the job's essential competencies, which enhances the content validity of the assessment.

Because structured interviews are a more valid predictor of future job performance, the actual return on investment associated with conducting structured interviews will inevitably be greater than with unstructured interviews. In the medium to long term, this will translate to greater performance, improved employee engagement, and lower attrition rates throughout the organization, more than justifying the additional effort associated with standardizing interviews in the first place.

section four

Reduced bias and adverse impact

The final key benefit of structured interviews is that they are widely regarded as being less biased than unstructured interviews. This is because structured interviews are designed to ask the same set of questions to all candidates, which allows for a more objective evaluation of candidates' responses. In contrast, unstructured interviews often involve ad-hoc questioning that can vary significantly from one candidate to another.

This lack of standardization can lead to unconscious biases influencing the interviewer's assessment of the candidate's suitability for the role.

By using structured interviews, organizations can reduce the risk of implicit bias influencing hiring decisions. This is particularly important for promoting diversity and inclusion in the workplace. Unconscious biases can lead to certain groups being disadvantaged in the hiring process, which can perpetuate a lack of diversity in the workforce. Structured interviews help to mitigate this risk by ensuring that all candidates are evaluated based on the same criteria, regardless of their background.

The implications for diversity and inclusion are significant. By using structured interviews, organizations can ensure that they are hiring the best candidates for the job, regardless of their demographic characteristics. This can help to promote a more diverse and inclusive workplace, which has been shown to lead to a range of benefits, including increased innovation, improved decision-making, and higher levels of employee engagement.

"Due to unconscious bias, the interviewer may be completely unaware that this is occurring, reducing the fairness of the assessment process."

Unstructured interviews, however, introduce the potential for adverse impact via unconscious bias. Because unstructured interviews allow interviewers to choose questions for each candidate, unconscious bias could result in certain candidates receiving harder questions or being assessed more harshly than others.

Therefore, from a diversity and inclusion perspective, it is imperative that structured interviews are created for any hiring process, and organizations must eliminate the use of unstructured interviews as soon as possible.

section five


Overall, the advantages of structured interviews are considerable and will almost always result in a greater quality of hire. Additionally, they leave less room for bias, reducing the potential for unconscious bias to invade the selection process and hamper diversity and inclusion efforts. Nevertheless, there are still hiring managers and HR professionals reading this article who will continue to use unstructured interviews in hiring, likely for many reasons.

Firstly, some hiring managers and HR practitioners may be concerned that structured interviews will offer a poorer candidate experience, and subsequently put off candidates. Although candidate experience is essential, you should not sacrifice validity for candidate experience. The objective of an interview is to improve the quality of hire, not provide entertainment to the candidate. Additionally, we would argue that the skill of the interview determines the candidate experience, not the structure of the interview, rendering this point moot.

Secondly, some organizations lack the expertise to create structured competency frameworks and thus stick with unstructured interviews for simplicity's sake. Although not every hiring manager or HR professional is trained in job analysis, everyone is capable of writing down a fixed set of questions and asking just those in an interview. Structured interviews don't need a comprehensive competency framework to be standardized; the fixed set of questions is more important.

Lastly, some hiring managers may believe that unstructured interviews serve as a better measure of the candidate's communication skills, as conversation can flow more freely. In reality, this doesn't improve the interview's ability to measure communication skills; it simply reduces the difficulty of the task. Highly communicative candidates will excel regardless of the interview format and will show their charisma and charm regardless. As a result, this benefit of unstructured interviews is entirely illusory.

Ultimately, organizations are free to select candidates however they like, provided they are in keeping with employment law. However, we believe that moving to structured interviews is the closest thing to a quality-of-hire hack that we know of, and all organizations should use structured interviews for all of their recruitment. The return on investment associated with simply writing down a set of questions and using them with every candidate is considerable, with virtually no downsides.

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