1. People on sidewalk are people. "Tweeters" may or may not be people. 2. A person can have at most one spot on a sidewalk, but multiple Twitter accounts. 3.

1. People on sidewalk are people. "Tweeters" may or may not be people. 2. A person can have at most one spot on a sidewalk, but multiple Twitter accounts. 3. People can organize an outpouring of opinion I Twitter. "Let's all tweet this at the same time" you can't organize happening to be on a sidewalk when the journo comes looking. 4. There is a certain personality type that joins Twitter. This is not the case to the same extent for sidewalks. 5. Tweet speed among Twitter users is more different (less than one to hundreds per day) than time spent walking sidewalks. 6. People on sidewalks are ASKED their opinion. People on Twitter speak without being asked. The people who aren't talking about a subject will have less strong views. 7. People on the sidewalk are in the same country as the journalist.