Two interviews can look the same from across the room. One person asks questions, another answers. But how the interview is run changes how well it predicts who will do the job and how fairly it treats candidates.
This guide explains the difference between structured and unstructured interviews, what the research says about each, and the parts that make an interview structured. The goal is to help you understand the method, not to sell you on a single rigid script.
Key takeaways
- Structured interviews use the same questions and the same scoring for every candidate; unstructured ones vary both.
- Research shows structured interviews predict job performance better, with a corrected mean validity of about .44 versus .33 for unstructured.
- Structure makes interviews more reliable: about 0.59 inter-rater reliability versus about 0.37 for unstructured.
- Reducing bias through structure is a documented benefit, with smaller differences between demographic groups.
- The core components are job analysis, standardized questions, anchored rating scales, and a predetermined scoring process.
Why it matters
Hiring decisions are expensive and hard to reverse. If your interview does not predict performance, you are guessing. Structured interviews give a more accurate read because they compare candidates on the same questions and the same standard. Google re:Work reports that structured interviews increase predictive validity and decrease differences between demographic groups, and notes these benefits have been documented by academic research over the last 20 years.
Fairness matters too, both ethically and legally. The U.S. Office of Personnel Management states that the structure and standardization of these interviews ensure validity, reliability, fairness, and practicality, which lets a structured interview meet legal and professional standards. When questions and scoring drift from one candidate to the next, you lose that protection and open the door to inconsistent judgments.
The differences, and what the research says
What a structured interview is
A structured interview uses a standardized questioning and scoring process for every candidate. Each person is asked the same predetermined questions in the same order, and all answers are rated on the same scale against the same standards for an acceptable answer. OPM states that this structure and standardization ensure validity, reliability, fairness, and practicality, which lets the interview meet legal and professional standards.
What an unstructured interview is
An unstructured interview varies the questions from candidate to candidate and has no fixed scoring. The conversation follows wherever it goes. This feels natural and flexible, but it makes candidates hard to compare because no two people are measured the same way. Without a shared scale, each interviewer leans on personal impressions.
Structured interviews predict performance better
In McDaniel and colleagues' 1994 meta-analysis, drawing on 245 validity coefficients from 86,311 individuals, structured interviews predicted job performance better than unstructured ones. The corrected mean validity was about .44 for structured versus .33 for unstructured. Without correction for range restriction the estimates were lower, around .31 versus .23. Figures vary by correction method, so cite them carefully.
Structure makes interviews more reliable
Reliability means different raters reach similar scores. The Judge, Higgins, and Cable review reports inter-rater reliability of about 0.59 for highly structured individual interviews, compared with only about 0.37 for unstructured ones. The authors note structured interviews are considerably more reliable, and that this difference in reliability may explain the difference in validity between the two formats.
Structure reduces bias
A review in Personnel Psychology by Levashina and colleagues identifies reducing bias through structure as a core, documented benefit. The review synthesizes how structure improves the reliability and validity of the employment interview, organizing the literature around the definition of structure, reducing bias through structure, situational versus past-behavior questions, and developing rating scales.
The components that make an interview structured
OPM lists the practical parts. Start by reviewing job-analysis material to decide which job-related competencies to assess. Then use standardized behavioral (past-experience) or situational (hypothetical) questions asked of all candidates. Pair them with customized anchored rating scales that define examples for each proficiency level, plus a predetermined scoring process. OPM notes that equal weights for competencies are generally the most effective and defensible approach unless you have a documented reason otherwise.
Where unstructured habits creep in
Structure can erode in small ways. An interviewer asks a follow-up of one candidate but not another. Someone skips the rating scale and scores on gut feeling. A panel debates a candidate before each member writes a score. Each shortcut pulls the interview back toward the unstructured end and weakens both its accuracy and its fairness.
How to structure an interview
Step 1: Start with job analysis
Before writing any question, review job-analysis material to determine the competencies the role actually requires. OPM places this first because every question and rating scale should trace back to a job-related competency. This keeps the interview focused on what predicts performance, not on personality or rapport.
Step 2: Write standardized questions
Create one set of questions tied to those competencies, and ask all candidates the same ones in the same order. Use behavioral questions about past experience or situational questions about hypothetical scenarios. Writing them in advance is what separates a structured interview from a conversation that wanders.
Step 3: Build anchored rating scales
For each competency, create a customized rating scale with anchors. Anchors are written examples that describe what a weak, average, and strong answer looks like at each proficiency level. Pair the scales with a predetermined scoring process. OPM notes equal weights across competencies are generally the most effective and defensible choice absent a documented reason otherwise.
Step 4: Train the interviewers
Walk every interviewer through the questions, the scales, and the anchors before they meet candidates. Google re:Work frames structured interviewing as using uniform methods: the same questions, the same grading scale, and decisions based on consistent, predetermined qualifications. Training keeps everyone applying that same standard.
Step 5: Score independently, then decide
Have each interviewer score answers against the anchored scale on their own, before any group discussion. Independent scoring protects the consistency that drives higher reliability and validity. Only after scores are recorded should the panel compare notes and make the hiring decision on the predetermined qualifications.
Do this
- Tie every question to a competency drawn from a real job analysis.
- Ask all candidates the same questions in the same order.
- Use behavioral and situational questions rather than vague chat.
- Score each answer on an anchored rating scale with defined examples.
- Have interviewers score independently before discussing candidates.
- Apply equal weights across competencies unless you document a reason not to.
- Train every interviewer on the questions, scales, and anchors first.
Common mistakes to avoid
Treating the interview as a free chat
Letting the conversation wander makes candidates impossible to compare on the same standard. Unstructured interviews vary the questions and have no fixed scoring, which is why they predict performance less well than structured ones.
Skipping the rating scale
Without anchored scales, interviewers fall back on gut feeling. That drops reliability. Highly structured interviews reach about 0.59 inter-rater reliability versus about 0.37 for unstructured, and that gap may explain the difference in validity.
Asking different candidates different questions
Even small tweaks break the comparison. The point of structure is that every candidate faces the same predetermined questions in the same order, scored against the same standards for an acceptable answer.
Discussing candidates before scoring
Group talk before scoring lets one loud voice anchor the rest. Score independently first so each rating reflects the answer against the scale, not the room's mood.
Writing questions with no link to the job
Questions that do not trace to a job-related competency add noise. OPM puts job analysis first precisely so the interview measures what the role requires.
Assuming structure removes all judgment
Structure guides judgment; it does not delete it. Interviewers still rate answers. The anchors and predetermined scoring exist to make that judgment consistent and defensible, not automatic.
Frequently asked questions
What is the main difference between structured and unstructured interviews?
A structured interview asks every candidate the same predetermined questions in the same order and scores all answers on the same rating scale against the same standards. An unstructured interview varies the questions and has no fixed scoring. The structure is what makes candidates comparable and, according to OPM, helps ensure validity, reliability, fairness, and practicality.
Do structured interviews really predict performance better?
Yes. In McDaniel and colleagues' 1994 meta-analysis of 245 validity coefficients from 86,311 individuals, structured interviews had a corrected mean validity of about .44 versus .33 for unstructured interviews. Without correction for range restriction the estimates were lower, around .31 versus .23. The exact numbers vary by correction method, so they should be cited carefully.
Why do structured interviews reduce bias?
Because every candidate is measured the same way, personal impressions carry less weight. Google re:Work reports that structured interviews increase predictive validity and decrease differences between demographic groups. A Personnel Psychology review by Levashina and colleagues identifies reducing bias through structure as a core, documented benefit of the structured employment interview.
What makes an interview count as structured?
OPM lists four parts. First, review job-analysis material to choose the competencies to assess. Second, use standardized behavioral or situational questions asked of all candidates. Third, pair them with customized anchored rating scales that define examples for each proficiency level. Fourth, follow a predetermined scoring process, usually with equal weights across competencies.
Why are structured interviews more reliable?
Reliability measures whether different raters reach similar scores. The Judge, Higgins, and Cable review reports about 0.59 inter-rater reliability for highly structured individual interviews versus about 0.37 for unstructured ones. The authors note structured interviews are considerably more reliable, and that this difference may explain the difference in validity between the two formats.
How do I keep an interview from drifting back to unstructured?
Write your questions in advance and ask all candidates the same ones in the same order. Use anchored rating scales for every competency. Have interviewers score independently before any group discussion. Train everyone on the method first. These habits hold the structure in place and protect both accuracy and fairness.
The bottom line
Structured and unstructured interviews are not just two styles. They are two different levels of accuracy and fairness. A structured interview asks every candidate the same job-relevant questions and scores them on the same anchored scale. The research is consistent: this approach predicts performance better, reaches more reliable scores, and reduces bias.
You do not need a heavy process to start. Run a job analysis, write your questions, build anchored scales, train your interviewers, and score independently. Get those parts right and the rest follows. Since structure starts well before anyone sits down to talk, a clean, consistent shortlist helps too. A tool like RefineCV formats candidate CVs into clear, comparable documents so your team reaches the structured interview faster.
Reach the interview faster
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Related reading: what actually predicts job performance and recruitment vs talent acquisition.
Sources
- U.S. Office of Personnel Management (OPM), Structured Interviews FAQ (2024): A structured interview asks every candidate the same predetermined questions in the same order and rates all answers on the same scale against the same standards, while unstructured interviews vary questions and have no fixed scoring. OPM states this structure and standardization ensure validity, reliability, fairness, and practicality.
- Google re:Work, A guide to structured interviewing (2024): Google defines structured interviewing as the same questions, grading on an identical scale, and decisions based on consistent, predetermined qualifications, and states structured interviews increase predictive validity and decrease differences between demographic groups, documented by academic research over the last 20 years.
- McDaniel, Whetzel, Schmidt & Maurer (1994), Journal of Applied Psychology 79(4), 599-616 (1994): In McDaniel and colleagues' 1994 meta-analysis of 245 validity coefficients from 86,311 individuals, structured interviews had a corrected mean validity of about .44 versus .33 for unstructured; uncorrected estimates were lower (about .31 vs .23), and figures vary by correction method.
- Judge, Higgins & Cable, The Employment Interview review (Illinois Institute of Technology) (2000): The Judge, Higgins & Cable review reports inter-rater reliability of about 0.59 for highly structured individual interviews versus about 0.37 for unstructured ones, noting structured interviews are considerably more reliable and that this may explain their higher validity.
- Levashina, Hartwell, Morgeson & Campion (2014), Personnel Psychology 67, 241-293 (2014): A Personnel Psychology review by Levashina and colleagues identifies reducing bias through structure as a core, documented benefit of structured interviews and synthesizes how structure improves their reliability and validity.
- U.S. Office of Personnel Management (OPM), Structured Interviews rating-scale guidance (2024): OPM specifies the components that make an interview structured: review job-analysis material to choose competencies, use standardized behavioral or situational questions asked of all candidates, and pair them with customized anchored rating scales and a predetermined scoring process, generally with equal weights across competencies.