McKinsey PEI – Depth of Follow-ups & Best Way to Structure Answers?

Q1: Follow-up types

Mix, but weighted toward judgment probes over factual questions.

Judgment probes (70% of follow-ups):

• "Why that approach?"
• "What were you thinking?"
• "What would you do differently?"
• "How did they react?"

Factual drill-downs (30%):

• "How long did this take?"
• "Who was involved?"
• "What exactly did you say?"

Factual questions surface when they sense vagueness or want to verify the story's real. Judgment probes are where they actually evaluate you.

Q2: Answering style

Short and direct. No STAR on follow-ups, that's for initial story only.

Answer structure:

• 1-2 sentences max
• Lead with reasoning on "why" questions, not more story
• Lead with outcome on "what happened" questions, not buildup

Example contrast:

• Weak: "Well, I was thinking about a few options, considered A and B, and ultimately..."
• Strong: "Chose 1:1s over group discussion because group dynamics amplified conflict. Separating them let me diagnose root concerns without posturing."

Prep for follow-ups

For each story, pre-write:

• Why you made each key decision (not just what)
• What you were thinking/feeling at turns
• What you'd do differently and why
• Specific metrics (timelines, team size, impact)
• Exact quotes or actions at critical moments

Practice with someone who interrupts and probes. Most candidates over-prep the initial story and freeze on follow-ups. Follow-ups are where interviewers decide if your story is real and if you think like a consultant.

1 - both

2 - STAR, but be flexible. If it's a short follow-up, no need to give a big, proper STAR, but if there are more and more questions in that area, it's worth taking a step back and presenting the situation properly. 

If you're working on the PEI, I would recommend this material I've built specifically for it:

• • Video Course: Master the McKinsey PEI

If you'd like to know more about it, don't hesitate to drop me a line.

Best,
Cristian

hey there :)

I would say you should expect a mix of follow ups, but they tend to go much deeper than most candidates anticipate. You will get both reflective questions like what were you thinking, why did you choose that approach, what would you do differently, and very specific detail questions like exactly what did you say, how did the other person react, how many stakeholders were involved. The goal is to test authenticity and depth, so they drill into your personal actions and decision making logic.

In terms of structure, start with a clear and concise STAR style narrative to set the scene, but keep it tight and spend most of the time on your actions and reasoning. For follow ups, do not repeat the full story. Answer directly and specifically, then add a short reflection if relevant. They care much more about your personal contribution and thought process than about the context.

The best way to prep is to take two or three strong stories per dimension and practice being pushed on them for ten to fifteen minutes straight. Ask a friend to challenge every statement with why, how exactly, what did you think, what was the risk, what was the alternative. If you can defend your story calmly and consistently under pressure, you are ready.

If you want, feel free to share your stories and I can stress test them with you.

best,
Alessa :)

Hi,

Great questions — and ones that a lot of candidates overthink, so let me try to simplify this for you. Have been on both sides of the PEI — as a nervous candidate and later as a McKinsey interviewer conducting dozens of them.

On the type of follow-ups you should expect:

It will be a mix of both — and that is by design. The interviewer is trained to probe until they get to the real depth of your story. Here is typically how it plays out:

1. Starts out with open-ended probes: "Walk me through your thinking," "Why did you choose that approach?" — these are designed to see if you can articulate your reasoning clearly and whether the story is genuinely yours.

2. Then shifts to specific, pointed follow-ups: "What exactly did you say to that stakeholder?" "What happened next?" "How did they react?" — this is where the interviewer is testing for authenticity and depth. If you lived the experience, you will remember the details.

3. Toughest follow-ups are the counterfactuals: "What would you do differently?" "What if the stakeholder had said no?" — these test your ability to reflect and think on your feet.

On structuring your answer:

You could indeed use a STAR framework to succinctly put across your story. However, some additional pointers below:

1. A clear, concise setup / teaser (45 seconds max) — Before going into the story itself, always set-up a teaser that presents what the situation was, what was at stake, and why was it challenging. This is typical "consultant-speak", meaning - layout the approach, before going into the details. Also, this way your interviewer gets the chance to indicate if your story is directionally on the path towards what he or she is looking for.

2. YOUR specific actions and thought process — this is 70-80% of your answer. What did YOU do (not your team), why did you do it, and how did you navigate obstacles along the way? Be specific.

3. The outcome and reflection — what happened, what did you learn, and what would you do differently?

On prepping for follow-ups:

1. Know your stories well: For each story, make sure you can answer: Who was involved? What did you specifically say or do? Why that approach and not another? What was the hardest moment? What surprised you? If you can answer all of these off the top of your head, you are ready.

2. Practice with someone who will interrupt you. The biggest mistake candidates make is practicing their stories as monologues. In a real PEI, you will get interrupted 4-5 times within a few minutes (and that's normal and by design). Get comfortable with that.

Two general tips:
 
(a) Ask for a time-out: Yes, that's right! Do not hesitate to ask for quick 20-second time-outs, even for PEI, this can be a game-changer! When the interviewer asks you a specific challenging question, take a moment to gather your thoughts and come back with a well thought-through structured answer!

(b) Write your stories down: Obviously you don't want a script that you've memorized, but it sure does not hurt when you are prepping, to write out a good overall storyline to frame your plot. In my own PEI prep, I spent quite some time detailing out the story in written form to make sure I had my story as well as responses to potential questions, clearly plotted out in my mind!

Hope that helps! Happy to connect over a session if you would like to do a mock PEI together — that is honestly the best way to prepare :)

All the best!

I actually interviewed with the firm last year and received an offer, and my experience was very different from what’s being described here.

The PEI is quite straightforward. Each pillar has a clear opening question, so you immediately know what they’re assessing. They’ll usually ask you to summarize your story in 30–60 seconds to see if it fits, then invite you to go deeper.

For the next ~10 minutes, the follow-ups are simple and logical:
Why did you choose X?
How did your team react?
What was an alternative?

They’re not trying to trap you — they’re helping you clarify your actions and thinking.

Some coaches tend to overcomplicate this and frame it as an intense interrogation. In reality, if you know your story well and can explain your reasoning calmly, you’ll be more than fine.

Just access the candidate portal they shared with you when they invited you to interview; it has 2-3 videos that answer your question perfectly. 

Hi there,

I'd say it's difficult to only pick one or the other. You should also read the interviewer so see the level of detail they're expecting from you. If you started with STAR, and they dig further, depending on the question, it can be another STAR or a matter-of-fact answer. I suggest practicing both.

It is a mix, but the open-ended probes matter most.

Factual questions like "how many people" or "what was the timeline" are easy. Answer directly and move on.

The harder ones are probing questions. "What were you thinking?" "Why that approach?" "What would you do differently?" These test how deeply you thought about the situation and whether you have real self-awareness.

Expect them to keep pushing. If you give a surface-level answer, they will ask "and then what" until they find the real you.

Here is how I would structure your answers

For the initial story, keep it simple. Situation, what you did, outcome. Two minutes max. Don't over-explain context.

For follow-ups, forget STAR. Just answer directly. If they ask what you were thinking, tell them. If they ask what you said, give them the actual words. Short, direct, honest.

The common mistake is turning every follow-up into a mini-STAR. That sounds rehearsed. Just answer the question.

For prep

Go deep on your own stories before the interview. Ask yourself:

• Why this decision and not something else?
• What was I feeling at each moment?
• What was the hardest part?
• What would I do differently now?

Practice with someone who will keep pushing "why" and "what else" until you run out of answers. That shows where your story is thin.

The best PEI answers feel like a conversation, not a presentation. Know your story deeply and you can handle any follow-up.

Feel free to reach out if you want to practice.