How to be a good interviewer, and how to prove it

How to be a good interviewer, in short: decide what the role needs before you meet anyone, ask every candidate about the same competencies, probe thin answers, write down what they actually said, and score each competency against a rubric you wrote first. The structure is what makes the judgment defensible.

What good interviewers do differently

• They decide what a good answer sounds like before the first candidate speaks, not after the last one leaves.
• They ask every candidate about the same competencies, in the same order, and rate them on one common scale.
• They write down what was actually said, then score alone before anyone in the room says a word.
• They treat a single odd moment as a question to ask, and only a repeated pattern as a reason to pass.

How to run an interview that produces a real decision

1. Name 4 to 6 competencies the role actually needs Work from the job, not the resume. If you cannot say what a person in this role will be doing in week 3, you are not ready to interview for it. Not "communication". Instead: "explains a technical trade-off to a non-technical stakeholder".
2. Write one question per competency, before you meet anyone Ask about past events for behaviour you can verify, and pose a hypothetical only where the role is genuinely new. OPM advises superlatives so the candidate picks one real incident. "Tell me about the hardest deadline you have missed." The word "hardest" does the work.
3. Write the rating scale before the questions leave your desk OPM recommends at least 3 proficiency levels and suggests aiming for 5 to 7, with at least 3 of them labelled. Describe in words what each labelled level sounds like. Label the bottom, the middle and the top. The unlabelled levels sit between them.
4. Ask, then probe the part that is thin A first answer is rarely complete. Probe it. OPM's rule is that probes may be tailored to what each person said, but their general meaning should not change between candidates. "What part of that was yours to deliver?" works on any vague answer.
5. Take notes as they speak, and say that you are doing it OPM calls detailed notes of observable behaviour crucial, and tells interviewers to inform the candidate that notes will be taken. Look up between sentences so it stays a conversation.
6. Score alone first, then reconcile with the panel Each interviewer reviews their own notes and rates the candidate before any discussion. Then the panel explores where the ratings disagree and reaches a consensus on each candidate.

Structured vs unstructured interviews

Fix the criteria before you meet anyone

Named evaluation criteria with weights that have to total 100, agreed before the first candidate is invited.

On paper this is a sheet you write once per role. In The Cognitive it is a template attached to the role: each criterion has a name, a description and a weight, and the weights must total 100 before the template saves. Everyone interviewing for that role scores against it.

The 6 mistakes interviewers make most

Ask what are top interview mistakes and you will get a list of 20 habits, most of them manners. The more useful list is shorter and older. The US Office of Personnel Management's guide to structured interviewing enumerates exactly 6 common interviewing mistakes, and they are all failures of judgment rather than etiquette.

These are the common interview errors that survive good intentions. You can be warm, prepared and genuinely interested in the person in front of you and still make every one of them. They are also the reason the method above exists: each of the 6 is blunted by something you do before the interview, not during it.

6 interview mistakes to avoid

• Relying on first impressions: deciding in the first few minutes on very little information.
• Negative emphasis: letting one unfavourable detail outweigh a page of favourable ones.
• Not knowing the job: interviewing for a role whose actual work you cannot describe.
• Pressure to hire: an open seat quietly lowering the bar you agreed on.
• Contrast effects: rating this candidate against the last one instead of against the bar.
• Nonverbal behaviour: reading confidence, honesty or fit into posture and eye contact.

Signs of a bad interview, and who is actually bad at interviews

Do

• The candidate is doing most of the talking, and you are mostly writing.
• Every competency on your sheet got asked about, even the one you find awkward.
• You asked at least one follow-up on every answer that arrived thin.
• Your notes contain sentences the candidate said, not adjectives you chose.

Do not

• You spent the first 10 minutes describing the company and the team.
• You improvised the questions and cannot remember what you asked the last person.
• You reacted mid-answer, so the candidate started steering toward your approval.
• You wrote the scorecard from memory two days later, after the debrief.

Interview red flags that are real, and 3 that are not

Every failure in every story belongs to someone else: a manager, a team, a client, the market.

Not that things never went wrong around them, but that they have no practised account of their own part in it. That account is what predicts learning.

What would you do differently if that project started again on Monday?

Confident claims that dissolve under one specific question about how the work was actually done.

The claim may still be true, but you now have no evidence for it. Score what survived the follow-up, not the original sentence.

Walk me through the first hour of that. What did you open first?

A pattern of short tenures with no explanation offered, across several unrelated employers.

A pattern, not one exit, is the signal. Contracts, layoffs, relocations and acquisitions all produce the same shape on a resume.

Take me through each of those moves. Which was your decision?

Sustained hostility about a former employer, beyond a frank account of why they left.

How they are likely to talk about you. Criticism with specifics and without contempt is not the same thing and should not be scored as one.

What did that manager get right?

Requirements that appear late and keep moving: scope, title, start date, reporting line.

Either the role was misdescribed to them or the negotiation started before the assessment did. Both are worth resolving now rather than at offer.

What has changed for you since the first conversation?

Nerves. Shaking hands, a lost thread, limited eye contact, a long pause before the first answer.

That they are being interviewed. It is not evidence about the work, and it maps onto anxiety, neurodivergence and cultural norms far more reliably than onto performance.

Offer the question again in writing, or move to an easier one and come back.

Weak small talk. No warmth in the first 2 minutes, flat answers about the weekend.

Almost nothing, unless small talk is part of the job. OPM names first impressions as the first common interviewing mistake for exactly this reason.

Skip ahead to a competency question and judge the answer instead.

Unconventional presentation: clothing, accent, a home background, a name you have to ask about.

Your own similarity bias, which OPM lists among the 6 common rating errors as Similar to Me. None of it is on your rubric.

Check whether you would have written the same note about the previous candidate.

Yellow flag or red flag

One awkward moment is a yellow flag: a question to ask, not a verdict. Red flags in an interview are patterns with more than one piece of evidence behind them. Score the pattern, never the moment.

What you may not ask, and what you may

This part is not optional and it is not covered by most interviewer guides. The US Equal Employment Opportunity Commission says pre-employment information should be limited to what is essential for deciding whether someone is qualified, and that questions about race, sex, national origin, age and religion are irrelevant to that. Asking them anyway can be used as evidence of intent to discriminate.

The EEOC also says employers are explicitly prohibited from pre-offer inquiries about disability, and should avoid asking about clubs, societies and other memberships that reveal a protected characteristic. You may ask whether someone can perform the job functions, and ask them to describe or demonstrate how they would, with or without reasonable accommodation. This is US federal law only. Check your state and country, and take advice.

How to evaluate a candidate after the interview

1. Rate every competency alone, immediately Before you speak to anyone, review your notes and rate each criterion. OPM is explicit that each panel member forms an independent evaluation first, without discussion.
2. Put the candidate's own words under each rating OPM requires ratings to be specific, defensible and supported by behavioural examples: the actual answer, why it applies to that competency, and why it earns that level. A rating with no quote beneath it is an opinion wearing a number.
3. Reconcile the panel by exploring the disagreements Do not average the scores. Where two interviewers rated the same competency differently, find out what each of them heard, then reach a consensus.
4. Re-read your ratings against the 6 rating errors OPM names rater bias, halo effect, central tendency, leniency, strictness and Similar to Me. Halo is the common one: a strong answer on one competency lifting all the others.
5. Decide against the bar, not against the last person Assess candidate quality by asking whether this person clears the standard you wrote down. Contrast effects are why the order candidates are seen in can move their ratings.

What the scorecard looks like when it is not on paper

Each criterion scored out of 5, an overall out of 100 weighted from the role's criteria, and a recommendation.

Any candidate evaluation software should force the step most teams skip: evidence under the rating. The Cognitive's scorecard scores each criterion out of 5, weights them into an overall out of 100, and adds a Verified in this interview section marking each resume claim as verified, refuted or unclear with the evidence behind it.

A candidate evaluation form you can copy

ROLE: [title]          CANDIDATE: [ref]          INTERVIEWER: [name]
DATE: [date]           ROUND: [screen / panel / final]

SCALE (write these once per role, not per candidate)
  5  Superior    [what a 5 sounds like for this role]
  4  [unlabelled, sits between 3 and 5]
  3  Satisfactory [what meets the bar]
  2  [unlabelled, sits between 1 and 3]
  1  Unsatisfactory [what falls short]

COMPETENCY 1: [name]                      WEIGHT: [n]
  Rating: [1 to 5]
  They said: "[quote from the answer, not a paraphrase]"
  Why that rating: [how the quote maps to this competency]

COMPETENCY 2: [name]                      WEIGHT: [n]
  Rating: [1 to 5]
  They said: "[quote]"
  Why that rating: [reasoning]

[repeat for each competency; weights total 100]

CLAIMS I COULD NOT VERIFY
  [claim] -> [what to ask in the next round]

RECOMMENDATION: [advance / hold / do not advance]
RATED BEFORE THE DEBRIEF: [yes / no]
  If no, say who you spoke to first and what they told you.

What is a shadow interview, and what is reverse shadowing

Interview shadowing A trainee interviewer sits in on a real interview run by an experienced one, to watch how questions are sequenced, how thin answers get probed, and how the rubric is applied to what was said.

Reverse shadowing flips it: the trainee runs the interview and the experienced interviewer observes, then debriefs. Where recordings exist, job shadowing can be done over the internet via video interviews reviewed afterwards, not live.

Train interviewers on real interviews, not role plays

A real two-way interview, with a recording and a speaker-labelled transcript afterwards for a trainee to review.

The cost of replacing an individual employee can range from one-half to two times the employee's annual salary, and that's a conservative estimate. Gallup

Build the interview before you run it

Rubric generator · Question generator · Scorecard generator · Interview kit

Frequently asked questions

What makes a good interviewer?

Preparation you can show afterwards. A good interviewer decides which competencies the role needs, writes one question and one rating scale for each before meeting anyone, asks every candidate about the same competencies in the same order, probes the answers that arrive thin, and records what was actually said. The warmth matters too, but it is the structure that makes the decision hold up.

What are the most common interview mistakes?

The US Office of Personnel Management names 6: relying on first impressions, negative emphasis, not knowing the job, pressure to hire, contrast effects, and reading too much into nonverbal behaviour. Every one is a judgment error rather than a matter of manners, and each is reduced by deciding what a good answer sounds like before the interview rather than after it.

What are the biggest interview red flags for employers?

Blaming every failure on someone else, claims that collapse under one specific follow-up, a pattern of unexplained short tenures, sustained hostility toward a former employer, and demands that keep shifting. Treat each as a question to ask rather than a verdict. A single odd moment is a yellow flag; a red flag is a pattern with more than one piece of evidence behind it.

How do you evaluate a candidate after an interview?

Rate every competency alone and immediately, before you speak to anyone else. Put a quote from the candidate under each rating and explain why it earns that level. Then reconcile with the panel by exploring the disagreements instead of averaging scores, and decide against the standard you wrote down rather than against whoever you interviewed last.

What is a shadow interview?

A shadow interview is one where a trainee interviewer observes an experienced colleague running a real interview, to see how questions are sequenced and how the rubric gets applied. Reverse shadowing is the opposite arrangement: the trainee leads and the experienced interviewer watches, then debriefs. With a recording, either can happen after the fact rather than live.

What are the signs of a bad interviewer?

Talking more than the candidate, improvising the questions so no two people are asked about the same things, reacting visibly mid-answer, skipping follow-ups, and writing the scorecard from memory days later. Most bad interview examples are not rudeness. They are an interview that produced a feeling rather than evidence anyone else can check.

What questions are employers not allowed to ask in an interview?

Under US federal law the EEOC says pre-employment questions should be limited to what is essential for deciding if someone is qualified, and that questions about race, sex, national origin, age and religion are irrelevant to that. Pre-offer disability inquiries are explicitly prohibited. You may ask whether and how a candidate would perform the job functions. Local rules vary, so check yours.

What are red flags for a candidate to watch for in an interview?

The reverse direction is real. Candidates watch for interviewers who have not read the resume, cannot describe the work, dodge questions about turnover or scope, or run a process that keeps changing. If you are interviewing well by the standard on this page, none of those will describe you. Interview red flags for employees are mostly just a badly run interview seen from the other chair.

Explore: What is a structured interview · Interview questions to ask candidates · The STAR method · Interview scorecard report · Panel interviews · AI interview cheating detection