The effectiveness of events has been measured thus far in terms of "quantity," including the number of attendeeｓ and exposure in the media. Contact Analytics is a tool to measure the effectiveness of an event from the perspective of "quality". This tool measures how much the attitudes and understanding of event participants have changed after attending an event, and tracks how long the effect lasts after a lapse of a certain period of time. These results reveal how much the event achieved its communication objectives, and enables us to make a proposal on improving the quality of events.