In order for your event to be a success you must measure the return on investment or the return on objective!
The ROI, return on investment, depends on what you want to achieve financially verse ROO which is return on objectives. Your goals decide if the ROI or ROO will be the savings gained from working with credible vendors, the new clients, existing client loyalty, increased sales, brand recognition, business awareness and other non tangible benefits.
The event design is much more then deciding the venue, food and the demographic that will attend, yes those are important but in order to measure your ROI you must have a measurement system in place before the event. Creating and implementing pre and post event surveys that target the issues, concerns and needs of the audience will ensure the measurement of the success of the event through the developed goals. For example, creating an interactive meeting in order to encourage and motivate employee and attendee participation is a way to create an event to achieve a goal.
Homework: What do you think needs to be done to measure your ROI or ROO?