Structured or Unstructured Interviews - Which Delivers Better Results?

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.

Key features of an unstructured interview:

• Each interview may focus on different aspects or topics
• Questions vary between candidates
• Conversational, flexible format
• Evaluation based on subjective impressions

Common unstructured interview questions:

• "Tell me about yourself"
• "What interests you about this role?"
• "What's your greatest weakness?"
• Random follow-up questions based on candidate responses

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.

Key features of a structured interview:

• Same questions for every candidate
• Predetermined evaluation criteria
• Questions directly related to job requirements

Common structured interview questions:

• "Describe a time when you had to work with a difficult team member. What was the situation, what actions did you take, and what was the outcome?"
• "Walk me through how you would prioritise multiple urgent projects with competing deadlines"
• "Give me an example of when you had to learn a new skill quickly. How did you approach it?"

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 here's the thing: research consistently shows unstructured interviews have lower predictive validity when it comes to identifying candidates who will succeed on the job.

For those who might not know what those numbers mean, structured interviews are about two times better at predicting job performance than unstructured ones.

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

The predictive validity data alone should be enough to convince you, but let's look at the other issues that can arise from unstructured interviews.

Where else do unstructured interviews go wrong

Bias creeps in everywhere: 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 unrelated to job performance.

Bias even creeps in with accents! Here's a video of our experts explaining how this happens:

You may think you're able to limit your bias and judge people fairly, but studies show most unconscious bias training is ineffective. A Yale University study found that scientists—who are 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 the identical "female" applicant (Proceedings of the National Academy of Sciences, 2012).

Inconsistent evaluation: 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?).

We've mentioned the higher predictive power of structured interviews, but let's dive deeper into the other benefits.

Superior predictive power

Research consistently shows that structured interviews outperform their unstructured counterparts:

✓ Predictive validity – Structured interviews achieve correlation coefficients of 0.43 compared to 0.24 for unstructured interviews (Harvard Business Review)

✓ Standardised measurement – Every candidate gets the same questions in the same order, creating fair comparisons and reducing random variables that could skew results.

✓ Objective scoring – Using consistent evaluation criteria minimises subjective judgments and personal bias, making results more reliable.

✓ Job-focused questions – Questions are specifically designed to assess the competencies that actually matter for success in the role, rather than general conversation topics. For example, if you need to assess teamwork ability, you'd ask every candidate: "Tell me about a time when you had to work with a difficult team member to achieve a shared goal. What was the situation, what did you do, and what was the outcome?" This targeted approach ensures you're measuring the exact skill you need, and every candidate gets the same opportunity to demonstrate it.

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.

Better business outcomes

The benefits extend beyond just accuracy and bias.

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 clear scoring make these decisions much quicker.

Structured interviews help ensure your process complies with employment laws by treating all candidates consistently avoiding potential legal issues.

And there is a knock-on effect of improved retention (which is what we all want!), if you're choosing the best suited candidates more reliably then they are more likely to stay longer.

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.

The evidence is clear: 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.

However, the story doesn't end there.

The most effective hiring process to get the most reliability and validity in the data you collect for each candidate (and to save your precious interview time) involves using something else alongside interviews.

Find out what that hidden piece of the puzzle is that provides the most effective method to assess the soft skills of your candidates.