Is McKinsey PST overkill for screening purpose?

McKinsey PST
Recent activity on Jan 01, 2019
3 Answers
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Anonymous A asked on Dec 29, 2018

Hi experts,

Is PST a bit of an overkill to check if the candidate has quantitative thinking? Normally, I feel I can solve any case math problem reasonably quickly, however, PST arugably requires months of mental math training. Hence two question:

- do you feel it's too much and it blocks potentially successful consultants who don't invest enough time to prepare for PST?

- How much math do you really need in consulting? Do you need mental math at all, or do you primarily rely on excel?

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Best answer
replied on Jan 01, 2019
BCG | Kellogg MBA |82% Success rate| 450+ case interview| 5+ year consulting | 30+ projects in ~10 countries

Hi there, it's a good question. To answer this question, we should understand why PST, then we can answer it. Here are the main reasons for PST or similar tests:

  • Measuring analytical and critical reasoning skills
  • Selecting candidates with the highest possibility to succeed in an interview
  • Checking how dedicated candidate is (Critical)

Now let's answer your questions based on those reasonings. Including your first comment I see 3 main questions and here are my answers:

  1. Is PST requiring more math skills than cases?
    • Not necessarily. To be able to perform consistently well in 4+ case interviews, you will still need very good math skills. Of course, we are using excel and even more advanced tools for sophisticated models but solid math skills are must have criteria to be able to quickly judge the business problems and develop the best hypothesis.
  2. How much do you need skills required in PST at consulting?
    • I would say it is highly relevant. Those kinds of tests are measuring critical reasoning and analytical skills which are the core for consulting. However, you are right, even if someone has good math skills and she is very good critical thinker, she still needs to practice significantly to be successful in the test.
  3. Is PST blocking potentially successful candidates?
    • Here I agree with you to some extent. Even best candidates who did not prepare for those tests enough can easily fail. Maybe they would perform very well at case interview. However, at this point companies are also measuring how dedicated candidates are and how much they care about this position? Therefore, those tests are one of the best ways for the first screening.

Hope it helps.


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replied on Dec 31, 2018
#1 Expert for Coaching Sessions (3.700+) | 1.300+ Reviews with 100% Recommendation Rate | Ex BCG | 8+ Years of Coaching

Hi Anonymous,

I agree with Guennael, consulting companies try at the same time to maximize the number of capable people and to minimize the number of people that aren’t a good fit for consulting that they hire. In terms of that, the PST provides quite a good screening. It also leads some smart people not to pass the test, but since the rules of the game are quite clear for these tests, this is part of the screening process as well: although it may take weeks to prepare, consulting companies consider as requirements for a good candidate also to take the time to prepare in advance.

In terms of the second question, it is true that the day to day job of a consultant requires a lot of Excel practice. However, it also requires to present in front of CXO levels, and you don’t want to get a math question and have to say “Let me go back to Excel to answer that”. In other words, good mental math is a key element of the credibility of a consultant in front of a client, and it is therefore a required skill that is tested during the application process.

Hope this helps,


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updated an answer on Dec 30, 2018
Ex-MBB, Experienced Hire; I will teach you not only the how, but also the why of case interviews

First off - whether it is "too much" or not doesn't matter, you need to take it for better or for worse

Second - if McK makes you take the PST, it is because it is the most efficient way to predict if someone will have the intellectual power to perform at the firm. Do talented people get unnecessarily weeded out at this stage of the process? Of course - but that is acceptable as long as few people make it who shouldn't.

Look, hundreds of thousands of people apply to MBB every year. Consultancies know they will each reject tens of thousands of qualified and smart people, but cannot do anything about that. Based on huge numbers of data points, PST and case interviews are just the best way to screen, so that's what they do. You want to play in their sand box, they make the rules.

As for your second question... we do (mental) math constantly!


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