Algorithm to detect a transit free network

Anurag Bhatia
In a recent Network AF podcast Avi Freedman (Kentik) joked with the guest about how he finds who is transit free / tier 1 network. He said, “I ask everyone who they think is a tier 1 network. Everyone includes their own name + other names”. Next, he ignores the self-nomination & looks at the common list to find who actually is a tier 1 network. This is funny, intuitive and gives some clue.