Marketing Mix Model Version Control

The Problem

The marketing mix models I worked with at Ipsos were large, complex Excel files shared across analysts in multiple international offices. There was no single place where version control, change documentation, or model structure lived consistently. Formulas were hardcoded throughout. Models were linked to external files that had moved or been renamed.

Models crashed constantly. Diagnosing a crash meant manually tracing through hundreds of cells with little documentation to lean on. Coordinating a fix across time zones took days. The same problems recurred because there was no structure preventing them.

What I Did

I treated it as a systems problem, not a one-off fix. I built a structured Excel template with a clear separation between inputs, calculations, and outputs — centralized assumptions in one place instead of hardcoded across dozens of cells, and removed all links to external files so each model was fully self-contained. Anyone could open it, follow it, and update it safely.

For coordination, I set up dedicated Microsoft Teams channels — one per model — and introduced lightweight change logs and naming conventions. Every change, question, and handoff was visible and stayed attached to the work it referenced. Cross-timezone collaboration went from reactive to traceable.

The Impact

Analytics model crashes were eliminated. With models self-contained and every change documented, analysts could pick up where someone else left off without a handoff call — across time zones, without coordination overhead.