Multi-touch attribution is considered as holy grail in advertising industry. As advertisers are targeting users with multiple advertisements across different platforms and publishers, understanding how each of these touch points contributes to conversion is crucial—but this understanding has traditionally come at the cost of user privacy.

Safeguarding individual privacy inherently means data minimisation i.e. limiting the collection and disposal of data. This principle has been a cornerstone of privacy advocacy and is even enshrined in regulations like the EU's General Data Protection Regulation (GDPR). However, a research published by Ponte et. al is challenging this fundamental assumption, introducing what they call the "Where's Waldo effect.

The promise of differential privacy is compelling. It offers a rigorous, provable guarantee of individual privacy, even in the face of arbitrary background knowledge. Rather than relying on anonymization techniques that can often be defeated, differential privacy works by injecting carefully calibrated noise into computations.

Differential Privacy (DP) is a mathematical framework that protects individual privacy in data analysis while allowing useful insights to be extracted. It works by adding carefully calibrated noise to data or query results, ensuring that including or excluding any single individual's data doesn't significantly change the analysis outcomes.