Structured vs unstructured interviews: which delivers the better results, and why?

When it comes to predicting job performance, not all interviews are created equal. The choice between structured and unstructured interviews can dramatically impact your hiring success, affecting your ability to assess both technical abilities and crucial soft skills.

Research consistently shows that one approach significantly outperforms the other in accuracy, fairness, and business outcomes. So let's try and settle this debate once and for all.

What even are structured or unstructured interviews?

Just before we get into the details and statistics of each method, let's quickly define exactly what we mean for each term for those who might be a little unsure.

Unstructured interviews: the conversation approach

Unstructured interviews follow an unstructured format. They flow naturally from topic to topic, with questions varying based on candidate responses. Questions aren't planned in advance, each candidate gets asked different things, and the evaluation is based on the interviewer's overall impression.

You might find yourself chatting about shared interests or diving deep into topics that weren't originally planned. This is the traditional approach many organisations used in the past.

Structured interviews: the systematic approach

As its name suggests, structured interviews take a more organised approach. Every candidate answers the same predetermined questions in the same order. Their responses are evaluated using a standardised scoring system that is used consistently across all candidates.

It might sound rigid, but structured interviews are designed around a simple principle: if you want to compare candidates fairly, you need to give them all the same test.

Unstructured interviews have less validity and more bias

You may be reading this thinking unstructured interviews feel like the better candidate experience or a more natural approach for you. They certainly offer flexibility and can make candidates feel more comfortable in a natural conversation setting.

But the research consistently shows unstructured interviews have lower predictive validity when it comes to identifying candidates who will succeed on the job.

What the research actually says about validity

The most widely cited figures come from Schmidt and Hunter's landmark 1998 meta-analysis, which synthesised decades of personnel selection research and found structured interviews had a validity of 0.51 compared to 0.38 for unstructured - making structured interviews roughly 34% more predictive.

Most subsequent research has found an even larger gap. McDaniel et al. (1994) found structured interviews were almost twice as predictive as unstructured ones, and Sackett et al. (2022) - the most recent large-scale meta-analysis - puts the figures at 0.42 for structured interviews versus 0.19 for unstructured, meaning structured interviews are around twice as effective at predicting job performance.

When different candidates answer different questions, you're essentially giving them different tests. This destroys both validity (how well are you measuring what you're trying to) and reliability (would you get consistent results if you repeated the process?).

It's worth noting that one influential update - Schmidt, Oh and Shaffer's 2016 re-analysis - applied a newer statistical correction and found the gap largely disappeared, with both interview types reaching 0.58. However, this finding has been contested. Sackett et al. (2022) specifically revisited those corrections and found they overcorrected for range restriction, restoring the gap between structured and unstructured interviews. The weight of evidence across the broader research literature still firmly favours structured interviews.

Despite all of this, around 44% of organisations still use unstructured interviews.

Bias plays a much stronger role in unstructured interviews

The predictive validity data alone makes a strong case, but it doesn't tell the full story. Without a structured format, unconscious bias heavily influences decisions. Research shows that 39% of interviewees get rejected based on their confidence level, their tone, or whether they smiled during the interview - factors with no bearing on job performance.

You may feel confident in your ability to judge people fairly, but studies show most unconscious bias training is ineffective. A Yale University study found that scientists - people trained to be objective - still showed significant gender bias when evaluating identical job applications. Both male and female science professors consistently rated a male applicant as more competent (4.05 vs 3.33 on a 5-point scale) and offered him $4,000 more in starting salary than an identically qualified female applicant (Proceedings of the National Academy of Sciences, 2012).

Structured interviews have much stronger validity and reliability

Superior predictive power

Research consistently shows that structured interviews outperform their unstructured counterparts:

Reduced bias, fairer hiring

Conversational interviews create multiple opportunities for bias to influence decisions. Interviewers might favour candidates who share similar backgrounds (affinity bias), let one impressive answer colour their entire evaluation (halo effect), or get distracted by irrelevant factors like where someone went to university or their hobbies.

Structured interviews don't eliminate bias entirely, but the standardised format significantly reduces how much it can influence outcomes.

Better business outcomes

The benefits extend beyond accuracy and fairness. Research shows that 35% of recruiters find evaluating candidates the most time-consuming part of hiring, while 28% struggle with making final decisions. Structured interviews with standardised scoring make both significantly quicker.

There's also a legal compliance dimension - treating all candidates consistently reduces the risk of discrimination claims and makes your process much easier to defend if challenged.

And if you're hiring better-matched candidates more reliably, the knock-on effect on retention follows naturally.

And the winner is... structured interviews

One of the main complaints of structured interviews, and why some interviewers prefer unstructured interviews, is because they feel too formal - they prefer free-flowing conversations.

But using structured interviews doesn't mean the entire interview process becomes robotic and impersonal. You can still have introductions, small talk, and team meetings to assess personality and cultural fit. The key is keeping these conversational elements separate from the standardised assessment of job skills.

This creates equal opportunity for every candidate to demonstrate their abilities based on job-relevant factors, while still allowing you to get a feel for their personality and team fit.

Conclusion and next steps

Structured interviews consistently outperform unstructured approaches across every meaningful metric. They're nearly twice as effective at predicting job performance, significantly reduce bias, ensure legal compliance, and create fairer outcomes for all candidates.

But even the best-structured interview has real limits, particularly when it comes to assessing soft skills like teamwork, problem-solving, and work ethic. Self-reported answers in an interview can only tell you so much, and by the time you're interviewing candidates, you've already invested significant time getting there.

The most effective hiring processes pair structured interviews with an earlier, scalable method of assessing these traits - one that doesn't rely on gut feel or self-report. Find out which approach the research shows is most effective: how to assess soft skills in candidates.

Primary author

Joshua Hancock

Digital Marketing Manager at Test Partnership. Over 7 years experience as a writer, content strategist, SEO and digital marketer.

Contributed to by:

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Ben Schwencke and Oliver Savill