Short answer: Structured vs unstructured interviews differ in what is decided before the interview. A structured interview asks every candidate the same job-related questions and rates each answer against a standard written in advance. An unstructured one leaves questions and judgement to each interviewer. Structured interviews have the highest average validity of the 25 methods reviewed (Sackett and colleagues, 2022).
Two recruiters interview the same candidate for the same warehouse role.
One asks about the candidate's last job, their hobbies and whether they are a team player, then writes down "good feeling".
The other asks five fixed questions tied to the role and rates each answer against a standard written the week before.
Both call it an interview. The research treats them as two different methods, with very different results.
On this page: What is a structured interview? · What is an unstructured interview? · How predictive are structured interviews? · Side by side · A warehouse example · Why the average is not the whole story · Why structure creates more comparable evidence · Advantages and disadvantages · What the research does not show · The practical catch: volume · How to make an interview more structured · Key takeaways · FAQ
What is a structured interview?
A structured interview asks every candidate the same job-related questions and rates each answer against a standard written in advance. The definition follows Campion, Palmer and Campion (1997). In practice, it has three features:
- A fixed set of job-related questions, built from what the role actually requires.
- The same questions for every candidate for that role.
- Criteria for a good answer, written before the first candidate is seen, so answers can be rated against the same standard.
The researchers behind the revised estimates link the method's strength to how it samples job behaviour. They describe questions in the "tell me about a time when…" style as one way to do this (Sackett and colleagues, 2023).
For frontline roles, structure can also cover practical requirements, asked the same way of everyone: the real start time, the real shift pattern, the physical demands of a full shift. Ask about the job's demands and the candidate's experience of similar work, never about health or medical conditions.
The Signal Gap, a term Radius Hire introduced in The Radius Papers 01 (2026), is the distance between what a hiring decision rests on and what predicts the outcome. Structure narrows it: it moves a requirement from "claimed" or "not covered" up to "structured".
What is an unstructured interview?
An unstructured interview is a conversation without fixed questions or agreed criteria. Each interviewer decides what to ask and how to judge the answers.
It can feel natural and personal. But two interviewers may ask different things, weigh answers differently, and reach different conclusions about the same person. Afterwards, it is hard to reconstruct what the decision was based on.
How predictive are structured interviews?
Moderately, and more than any other method in the revised research. Validity here is an estimated correlation between what a selection method says about candidates and their rated job performance, corrected for measurement error: 0 means no relationship, 1 a perfect one. On the revised 2022 estimates, structured interviews average 0.42, a moderate link to job performance, and the highest of the 25 methods reviewed. Unstructured interviews average 0.19. Years of job experience average 0.07 (Sackett and colleagues, 2022).
In plain terms, that is enough to improve the odds across many hires, not to predict any one person. These are averages from many studies, mostly outside the Netherlands, and they measure overall job performance, not retention.
Structured vs unstructured interviews: side by side
For more than twenty years, the standard reference on selection methods was a 1998 summary by Schmidt and Hunter. In 2022, Sackett, Zhang, Berry and Lievens showed that a statistical correction for "range restriction" had often been applied in the wrong way, which inflated many estimates. Their revised figures are the ones used below.
| Structured interview | Unstructured interview | |
|---|---|---|
| Questions | Fixed, job-related, the same for every candidate | Chosen by each interviewer, often different per candidate |
| How answers are judged | Against criteria written before the first candidate | By the interviewer's overall impression |
| Record afterwards | Answers and ratings per question | Often a short note or a general verdict |
| Comparability of candidates | High: same questions, same standard | Low: different questions, different standards |
| Average validity, revised estimate (2022) | 0.42 | 0.19 |
| Earlier estimate (1998) | 0.51 | 0.38 |
| Likely range across settings (80% credibility interval) | 0.18 to 0.66 | Lower end just below zero (minus 0.01) |
| Effort at volume | Higher: questions, criteria, training and records needed | Lower to set up, harder to review or defend |
Validity figures: Sackett and colleagues (2022), restated in Sackett and colleagues (2023); Schmidt and Hunter (1998).
For context, the revised estimate for years of job experience is 0.07 (1998: 0.18), one of the lowest of the methods reviewed.
The researchers conclude that the methods at the top of the list are specific to the job: structured interviews, job knowledge tests, work samples and empirically keyed biodata (background questions scored on what has predicted performance before). On average, these do better than general measures such as cognitive ability or personality (Sackett and colleagues, 2023).
A warehouse example: the same topic, asked two ways
These questions are illustrations written for this article. They are not a validated assessment.
Unstructured: "So, tell me a bit about yourself. Do you think you would be good in a warehouse?"
The answer depends on how confident and talkative the candidate is. There is no standard to judge it against, and a second interviewer might ask something completely different.
Structured: "It is hour six of an eight-hour shift. Your pick rate is behind, and a pallet is blocking the aisle you need. Your supervisor is at the other end of the building. What do you do?"
Every candidate gets the same question, with or without warehouse experience. The interviewer rates the answer against a standard written in advance, for example:
- Strong: puts safety first in a specific way, for example keeps to a safe route or reports the blocked aisle, and says how they would let the team know about the delay.
- Acceptable: chooses the safe option, with less detail.
- Weak: works around the blockage to catch up, or cannot say what they would do.
Why the average is not the whole story
The authors are explicit that the structured interview figure has a wide spread. They write that its validity is better read as ".42, plus or minus .24" than as a fixed number (Sackett and colleagues, 2023).
They suggest several reasons for that spread:
- one label, "structured interview", covers different practices
- some procedures are built to a higher quality than others
- study designs differ
- jobs differ
They present the spread as a reason to invest in careful design.
They also caution against treating any single finding as a rule. The choice of method should weigh validity together with cost, time, testing volume, differences between groups of applicants, and how applicants react (Sackett and colleagues, 2023).
Why structure creates more comparable evidence
Unstructured interviews average 0.19 and structured ones 0.42 (Sackett and colleagues, 2022). The two figures come from different studies, so read this as direction, not proof: structure appears to explain much of what makes an interview predictive.
There is also a practical reason, separate from the statistics:
- When every candidate answers the same questions against the same written standard, candidates become comparable.
- The decision becomes reviewable.
- A record exists. Six months later, someone can see what the decision was based on.
What are the advantages and disadvantages of structured interviews?
Structured interviews give you comparable, reviewable evidence, at the cost of more effort to set up and run.
Advantages:
- The highest average validity of the methods reviewed in the revised research, with a moderate link to job performance.
- Candidates become comparable: same questions, same standard.
- Decisions become reviewable, with a record of answers and ratings.
Disadvantages:
- More effort to set up and run: questions, criteria, training, calibration and records.
- Hard to sustain at high volume with fixed recruiter hours.
- Results vary widely between settings, and the evidence for inexperienced applicants is unclear.
What does the research on structured interviews not show?
It does not show how well structured interviews predict attendance or retention, how well they work in Dutch frontline roles or with inexperienced applicants, or whether they make hiring fairer. This is where many summaries stop too early.
- The outcome is overall job performance, usually rated by supervisors. The estimates do not tell you how well a method predicts attendance, early leaving, safety incidents or retention. In frontline operations, those are often the outcomes that matter most.
- These are not Dutch frontline studies. They are averages across many studies, mostly from outside the Netherlands and across many occupations. The authors recommend looking beyond the overall average to more specific findings, and to evidence from your own setting (Sackett and colleagues, 2023).
- Entry-level hiring is a known limit. The authors say current research cannot readily show whether structured interviews designed for inexperienced candidates reach similar validity (Sackett and colleagues, 2023).
- Newer methods are not settled. The researchers say they are eager to see newer methods, such as asynchronous video interviews and language-processing-based scoring, compared with traditional ones, but a body of validity evidence on them has not yet accumulated (Sackett and colleagues, 2023).
- Fairness is a separate question. US research reports smaller average score differences between groups for structured interviews than for cognitive ability tests (Sackett and colleagues, 2022). Smaller score gaps are not the same as fairer hiring decisions, and The Radius Papers 01 found no verified evidence that structured interviews reduce discrimination.
Treat the research as direction, not as a promise. A process called "structured" does not ensure structured results. Only local records of outcomes can show what your own process delivers.
The practical catch: volume
The researchers behind the revised estimates note that, in their traditional in-person form, structured interviews are generally not a viable strategy for high-volume jobs, and that when technology takes over delivery, validity has to be checked again (Sackett and colleagues, 2022).
A fixed question set, asked of every candidate and rated consistently, is a standing weekly workload. It also needs training, calibration and records. Where recruiter hours are fixed, structure is often the first thing to give way. This is the core operational challenge for frontline hiring.
How do you make an interview more structured?
Write the questions and the rating standard before the first candidate, ask them the same way every time, and record the answers. You do not need a full redesign to start.
- Write the requirements down, in the words a supervisor would use. Start with the handful that decide whether a hire works out.
- Write one question per requirement that currently rests on a claim or is not covered at all. Keep questions short, in plain language, and easy to answer on a phone.
- Ask every candidate the same questions, in the same order and the same way.
- Write a rating standard before the first candidate. For each question, give a short example of a strong, an acceptable and a weak answer.
- Record the answers and the ratings, not just the final decision. Set how long you keep them, and document the period.
- Check consistency. Have two reviewers rate the same answers from time to time, and discuss where they differ.
- Consider a second job-specific check, such as a work sample. The 0.42 average describes the interview used alone (Sackett and colleagues, 2022), and what a combination adds depends on the methods combined. In ongoing work that is not yet final, the researchers report an average validity of 0.47 across combinations of one to five widely used predictors (Sackett and colleagues, 2023).
- Record outcomes for the people you hire, such as attendance, early leaving and a supervisor rating at a fixed point. Check over time whether what the interview collected predicts them.
Key takeaways
- A structured interview asks every candidate the same job-related questions and rates each answer against a standard written in advance.
- Structured interviews average 0.42, a moderate link to job performance; unstructured interviews average 0.19 (Sackett and colleagues, 2022).
- The likely range across settings is wide (0.18 to 0.66; Sackett and colleagues, 2023), so design quality matters. So does checking your own results.
- The research covers overall performance, mostly outside the Netherlands. It does not cover attendance or retention, and says little about inexperienced applicants.
- Structure makes candidates comparable and decisions reviewable. It has not been shown to remove bias.
FAQ
What is a structured interview?
A structured interview asks every candidate the same job-related questions and rates each answer against a standard written in advance.
Are structured interviews more predictive than unstructured interviews?
On average, yes: 0.42 against 0.19 for overall job performance, across different sets of studies (Sackett and colleagues, 2022). Results vary between settings.
What is a credibility interval?
The range in which the true validity is expected to fall in 80 percent of settings. For structured interviews it runs from 0.18 to 0.66 (Sackett and colleagues, 2023), so how well the interview is built matters.
Do structured interviews work for inexperienced applicants?
It is unclear. The researchers say current studies cannot readily show whether structured interviews designed for inexperienced candidates reach similar validity (Sackett and colleagues, 2023).
Will my own structured interviews reach 0.42?
Not necessarily. 0.42 is an average across many studies, and the likely range runs from 0.18 to 0.66 (Sackett and colleagues, 2023). Only local records of outcomes can show what your own process delivers.
How do you make an interview more structured?
Write the job requirements down, ask every candidate the same questions tied to them, write the criteria for a good answer in advance, and record answers and ratings.
Sources
- Sackett, P. R., Zhang, C., Berry, C. M., and Lievens, F. (2022). Revisiting meta-analytic estimates of validity in personnel selection: Addressing systematic overcorrection for restriction of range. Journal of Applied Psychology, 107(11), 2040 to 2068. DOI 10.1037/apl0000994
- Sackett, P. R., Zhang, C., Berry, C. M., and Lievens, F. (2023). Revisiting the design of selection systems in light of new findings regarding the validity of widely used predictors. Industrial and Organizational Psychology, 16(3), 283 to 300. Open access. DOI 10.1017/iop.2023.24
- Schmidt, F. L., and Hunter, J. E. (1998). The validity and utility of selection methods in personnel psychology. Psychological Bulletin, 124(2), 262 to 274.
- Campion, M. A., Palmer, D. K., and Campion, J. E. (1997). A review of structure in the selection interview. Personnel Psychology, 50(3), 655 to 702.
- Radius Hire (2026). The Radius Papers 01: A New Standard for Frontline Hiring. Sections 3.1 to 3.7 and 4.2 to 4.3.