1. What is it?

This type of question gives you a particular set of facts / data and asks you to identify what could be the causing reason for the facts. See the illustrative picture below.

management consulting prep pst root cause 2

1.1  Question format

“Which of the following reasons, if TRUE, will help explain the Facts …”?
“Which of the following does NOT explain the Facts …”?
“Which of the following points is NOT a valid reason for the Facts …”?

1.2 Differences between Root-cause reason and Fact-based Conclusion

These questions are usually mistaken for Fact-based Conclusion, which is very dangerous. Carefully review the differences summarized in the table below.

1.3 Illustrative example

Facts provided: Visits to the website MConsultingPrep were relatively low last month.

Root-cause Reason Question: What reasons, if TRUE, would help explain the low traffic to MConsultingPrep last month?

Correct answers can be any of the following:

  1. Quality of contents has been bad
  2. Because of technical issues, some particular visitors could not access the website
  3. Last month was December (when overall market demand for job prep materials is lowest in the year)
  4. The entrance of other new consulting prep blogs

Face-based Conclusion Question: What can be concluded from the data provided?

All of the above statements can very much be the reason for the stated fact but NONE of them can be concluded.

Example of a statement that can be concluded: If the conversion rate stays constant across the years, revenue last month was relatively low.

2. Common Pitfalls

What makes a statement NOT a potential reason for a particular fact?

There are two ways a statement cannot be the potential reason: (1) Wrong Subject and (2) Wrong Trend.

  1. A statement is (1) Wrong on Subject when the subject is irrelevant; usually, the statement will have zero effect on the stated fact.
  2. A statement is (2) Wrong on Trend when the direction is reversed; usually, the statement will have a reversed effect on the stated fact

Illustrative example

Let’s continue with the simple example started above.
The Stated Fact: Visits to the MConsultingPrep blog were relatively low last month.

(1) Example of a “Wrong Subject” statement: “The entrance of new Investment Banking Prep blogs

Here the subject “Investment Banking Prep blogs” is irrelevant to the stated fact. The statement (1) will have zero effect on the stated fact.

(2) Example of a “Wrong Trend” statement: “The exit of other existing Consulting Prep blogs”

Here even though the subject “Consulting Prep blogs” is relevant, the trend however is reversed. The exit of Consulting Blogs will contribute to the increasing visit trend. Therefore the statement (2) will have a reversed effect on the stated fact.

3. Challenging Example

You may find the above example too simple to prompt such a complicated approach. We picked a simple example to better convey the concept to you first. However, the same concept on the real McKinsey Problem Solving Test at times can be much more confusing. Let’s try one!

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