Jonathon Wells, Senior Vice President, Data Science, Nielsen, answers five questions to better understand the important role of identity system in audience measurement. 

Here are the five questions: 

• What are the market changes that have made an identity system change important for audience measurement? 
• What is difficult about associating an individual with devices?  
• What is an identity graph? 
• What is the role of the identity system in audience measurement? 
• What is different about Identity for targeting vs identity for measurement?