I was on the Upper West Side at 105th street recently when I came across a street cordoned off by the police. A small crowd had gathered.

“What’s going on,” I asked.

Three people pointed to their phones and said: “two guys were shot.”

They were all looking at Citizen, a social network app which maps crime reports.

It’s an incredible thing to be 340 feet away and not know a shooting happened.

And the police on the corner refuse to tell you.

But the big data “crowd” had the answer.

Looking at Citizen it’s hard not to want to aggregate the information or break it down by kind of crime or see volumes by location or trends over time.

Citizen doesn’t make that kind of data available to users.

I suspect that they will sell trend data to developers, realtors and companies looking to analyze where they should open stores or offices.

The data could also be used to generate automated news articles.

It underscored that we are still early in the game of harvesting alternative data.