[Thersites]

My understanding is that the metrics used to calculate ROI differ from client to client. It's more an art (or scam) than a science, with a ton of grey area. Whatever metric the client's boss is really into at the moment can be marketed hard and inflated using unverifiable data if needed. A lot of people are incentivised to tell the story that influencers provide value to brands. I believe that this is less and less true every day.