Result-based Event Pricing

Imagine event organizers pricing events (e.g. trade shows) based on the results attendees/exhibitors/sponsors get.

As an event creator, could you, or would you, price your events in such a way?

As an event sponsor or exhibitor, would you be willing to pay in this way for results?

How would you measure the results and set the price?

Interested in how event professionals might handle this.