McKinsey takes a structured approach to solving problems that includes breaking down larger issues into smaller pieces. Those components of the problem are arranged into an "issue tree" with the biggest, overarching issues at the top. Those are then supported by additional, increasingly specific, tactical, broader levels of supporting details. I will devote a future post to these issue trees.
Top-Down ApproachThis means the problem solving begins at the "top" or with the highest-level, overarching question or theme, also known as the governing thought. From there, the problem is broken down, identifying and developing the elements the next level down, with special focus on the critical or vital few drivers of impact. Only after those key elements have been determined does the focus shift to tactical details. The process is repeated, adding additional levels down the tree the tree is exhaustive.
Bottom-Up ApproachThis is the opposite of the top-down approach and, as the name implies, begins with the tactical, granular, specific details. In this case, the work focuses on starting with a laundry list of issues, then organizing them into like groups, or "buckets". Those buckets can often be grouped further, building levels up the tree, until, finally, the key drivers and governing thought are reached.
Top-Down vs. Bottom-Up ThinkingThe simplest way to summarize the difference is this: working at the top is considered strategic, while working at the bottom is tactical. McKinsey consultants are encouraged to think strategically vs. tactically. Here are some reasons why...
Why the Top-Down Approach is PreferredThere is a strong bias toward top-down thinking at McKinsey because it a) is logical, with a structured approach and b) starts by defining the most important questions and issues first. The assumption is that if enough smart, experienced, hard-working consultants and clients align on the governing thought, the rest of the work that follows will be directionally correct.
Working top-down helps ensure that the questions asked and issues raised are completely exhaustive. Less relevant ones might eventually get trimmed, but they will at least have been considered. Top-down thinking also limits wasted work because only those topics deemed relevant and important to the governing thought need to be developed in detail.