Methods and apparatus to perform identity matching across audience measurement systems

A method to perform identity matching, the method comprising:

• identifying, by executing an instruction with a processor, a first one of a plurality of search spaces in a data structure based on a query event, the data structure based on audience measurement events corresponding to a first audience measurement system, the query event corresponding to a second audience measurement system;
• determining, by executing an instruction with the processor, the query event and a first audience measurement event in the search space are a candidate match when a distance between the query event and the first audience measurement event satisfies a threshold;
• generating, by executing an instruction with the processor, a profile for a first user identifier based on the audience measurement events associated with the first audience measurement system, the first user identifier associated with the first audience measurement system, the first user identifier linked to a second user identifier associated with the second audience measurement system based on the candidate match, the profile including the second user identifier but not the first user identifier;
• and
• providing, by executing an instruction with the processor, the profile to the second audience measurement system without the first user identifier.

A non-transitory computer readable medium comprising instructions that, when executed, cause a machine to at least:

• identify a first one of a plurality of search spaces in a data structure based on a query event, the data structure based on audience measurement events corresponding to a first audience measurement system, the query event corresponding to a second audience measurement system;
• determine the query event and a first audience measurement event in the search space are a candidate match when a distance between the query event and the first audience measurement event satisfies a threshold;
• generate a profile for a first user identifier based on the audience measurement events associated with the first audience measurement system, the first user identifier associated with the first audience measurement system, the first user identifier linked to a second user identifier associated with the second audience measurement system based on the candidate match, the profile including the second user identifier but not the first user identifier;
• and
• provide the profile to the second audience measurement system without the first user identifier.