There are no good national numbers on police conduct. Even the government's most basic statistic - the number of people killed by police - [is] way off. The White House says it wants to change that with the Police Data Initiative ... whose final report called for greater data transparency as a means to build trust between police and communities. The Police Data Initiative encourages departments to anticipate the kind of numbers their communities want to see, and provide them, preferably in database format. As an example, the White House cites the online data portal on police shootings set up by the Dallas Police Department. But there's a caveat, here: This is all voluntary. The White House says 53 jurisdictions so far have pledged to share this kind of data. But an additional 17,000 or so law enforcement agencies have not yet signed on, and they account for about 85 percent of the country's population. Openness to providing data seems to be most prevalent in police departments that are already in cooperative relationships with the federal government. Many of them receive federal grants, observes David L. Carter, a professor in the School of Criminal Justice at Michigan State University. "In many cases, progressive police executives feel it's 'the right thing to do,' and will volunteer," says Carter in an email. But he thinks others may take a pass. The result? There may be good stats on places like LA and Dallas, while thousands of smaller communities ... will continue to be white spaces on the statistical map.