CPA (cost per acquisition)

CPA is the number closest to what a client actually wants to know: what did each customer cost? The "acquisition" is whatever the campaign was set up to drive, whether that's a sale, an app install or a booked appointment. Agree what counts before the campaign starts, not after.

Influencer CPA needs attribution: discount codes per creator, tracked links, or post-campaign surveys. Codes get shared on coupon sites, so they overstate some creators; links miss people who search for the brand later, so they understate others. Say which method you used.