What is iROAS?

Return on ad spend calculated using only the incremental revenue driven by advertising, not total attributed revenue. If a campaign reported $500,000 in attributed revenue and cost $100,000, the attributed ROAS is 5x. If an incrementality test shows that only $150,000 of that revenue was truly caused by the ads, the iROAS is 1.5x. The gap between attributed ROAS and iROAS is often large, especially for retargeting.