Data aficionados are fond of the saying "The plural of anecdote is not data," because it affirms the importance of basing decisions and judgments on wide-scale, objective measurements.
This is not a bad philosophy. As a civic society, we don't want to enact new laws or divert massive funds based on that crazy thing that happened to your uncle (or on Tumblr) two-or-15-years-ago. However, the perception that anecdotes – i.e. individual stories and observations – are inherently different if not inferior to data when it comes to conveying truth has two harmful implications:
It's easy to assume in today's smartphone/Internet-of-Things/always-on age that the process of data collection is professional, objective, and complete. But the recent revelation that there has been no official collector of something as important and countable as police shootings should be a reminder of how the very act of counting is inherently subject to political priorities and biases.
Likewise, the initiative taken by public advocates and journalism organizations to independently collect and analyze this data is evidence of how watchdog instincts and a structured approach can turn anecdotes into vital data.
As you begin learning and practicing data journalism, realize that every row in a database is a story. As you become more experienced, you'll learn that important stories can be found in the political reasons for the data collection, the technical steps of its collection process – even the underlying details of the database schema – and, of course, the data that isn't collected.
Nate Silver's take on Wolfinger, via his FiveThirtyEight opening essay, "What the Fox Knows":
Wolfinger’s formulation makes sense: Data does not have a virgin birth. It comes to us from somewhere. Someone set up a procedure to collect and record it. Sometimes this person is a scientist, but she also could be a journalist.