Ambassador Program Performance

How are you proving that your ambassador program is worth a budget? 

What KPIs and metrics are you tracking to ensure that you are getting an ROI? 

My other question is, how are you determining the goals of your KPIs and metrics for your ambassador program?

EX: John Doe has 1.4 million followers on Instagram - we want him to reach XXX amount of people, have XXX amount of interactions, and XXX amount of users convert to XXX amount of revenue.