The campaign with the best return on ad spend is often the one quietly wasting your budget. A landmark eBay experiment showed branded ads taking credit for sales that were always coming. Here is how to spot the same pattern in your own account and measure what your ads actually cause.

A $20M brand was pouring budget into the channel their dashboard crowned the winner. The mix model told a different story, and the real growth lever was sitting starved at the bottom of the report. Here is how to tell whether your marketing is actually working, why your agency and in-house team usually can't answer that, and which third of your budget is doing the work.

Six years ago, a client called share of voice the biggest BS metric in marketing. By the end of the engagement, his campaign efficiency had improved 300%. Here's why the metric still wins in 2026, and how to build SOV across every channel that matters now, including AI search.