What does it mean to "Trim an Issue Tree" at McKinsey?

As covered previously, issue trees are used to solve complex problems by breaking them down into their component parts.  Your McKinsey boss might ask you to prioritize efforts by trimming an issue tree.  In this post, I'll explain what that means...

What does it mean to trim an issue tree?

Once the issue tree has been developed, the team will develop hypotheses on which issues and sub-issues are likely to drive the most and least impact.  The vital few, high-impact issues will get prioritized and low-impact or irrelevant items should be cut.  Extending the tree metaphor, cutting issues and sub-issues is often referred to as "trimming" or "trimming branches from" the issue tree.

Why is this important?

Any team only has a finite amount of time, effort, and resources to dedicate to problem solving.  Trimming less promising branches from the issue tree allows the team to prioritize and focus their work on the vital few issues and sub-issues that are expected to create the greatest impact.

How does a team determine what to trim?

Building and trimming issues trees are hypothesis-driven exercises.  Background information, preliminary data analyses, and expert opinions can be used to inform and update these hypotheses.  Rarely, as the problem solving and analyses continue, new information could result in issues or sub-issues being reconsidered and added back to the issue tree.

Issue Tree Trimming Example

An example of an easy branch to trim would be an issue tree dealing with how to increase the profitability of a client company.  One way to increase profits is to increase revenues by increasing prices.  But if the client is selling a commodity good, prices are set by the market, so they will have no control over pricing.  So, the "increase prices" branch is irrelevant can be trimmed from this particular issue tree.