As an introduction, I recommend in general using the PARADE framework for structuring your McKinsey PEI, and talking about your impact usually goes into the “A” for “Anticipated consequence”.
Since the “PAR” is just to give your interviewer a general understanding of the overall situation within 1-2 minutes (and since the core part of your evaluation is based on your specific “Actions” and “Decision-making rationale”), I am perfectly fine with summarizing your impact on a situation more or less in one sentence as a start.
However, since the “Anticipated consequence” demonstrates the real-life impact of you, it’s common that interviewers follow-up on that and want to understand your real-life impact in more detail. Continue reading How to demonstrate your impact in the McKinsey PEI