Facebook Lookalike Audience Saturation Part 1

This post encapsulates some theories as to why marketing performance may suddenly decline after running a particular audience for some time. Also known as audience saturation.

While this post focuses on the mechanics of lookalike audiences, the concept can be applied to any audience, with minor nuances in the mechanics. For example, audience excavation in non-lookalikes occurs as Facebook obtains data on users who fit those audience profiles (e.g. a user mentioning the word “fitness” in a message, and thus being tagged as a user interested in fitness).

What is a lookalike audience?

A lookalike audience is the term given to a group of users that Facebook has determined “look like,” or have some set of characteristics in common with a custom or “seed” audience. Lookalike audiences are referred to by different monikers, such as “actalikes’ in Pinterest, or ‘audience hints” in Google UAC.

Seed audiences are users grouped by some particular behavior or trait that is deemed valuable by an advertiser. While the most common seed audience and lookalike is users who have purchased, seeds can be grouped by anything meaningful to the advertiser, including users who share a combination of behavior correlated with or known to be associated with high monetary value.

Lookalikes are created when an advertiser uploads a seed audience to Facebook and selects a lookalike percentage(s) and country source(s). Facebook then searches for those users in…