Measuring success starts before the activation, not after. Decide in the brief what you want to know.
Reach: how many people saw or experienced the activation.
Engagement: how many people actively took part.
Conversion: how many took a follow-up action (sign-up, discount code, website visit).
Sentiment: what they say about it, online and on the spot.
Combine hard figures with qualitative data. Three good quotes from visitors carry more weight than an average waiting time. After every activation we deliver a report along these four axes, including photo and video content.