Since Michael Brown's death in Ferguson, Mo. on Aug. 9, police have shot and killed people who were apparently unarmed in Los Angeles; San Jose; Victorville, Calif. and South Salt Lake, Utah. For two days, police in New Orleans did not make public the fact that an officer had shot a man in the head. He is expected to survive the injury.

News reports of officer-involved shootings are fairly regular across the country, but there are no national, comprehensive statistics on these incidents, so it is impossible to say how frequently they happen. Information about those struck by police bullets is also unavailable -- whether they are unarmed or carrying a weapon, criminals or innocent bystanders, black or white. Reliable data would make it easier for citizens to know when officers are acting recklessly, and for police departments to develop methods of avoiding the use of lethal force.

The FBI collects data from police departments on all kinds of crimes, including hate crimes violence against police officers, but the bureau is not required to compile statistics on officer-involved shootings. Data from the state of New York shows that the targets of police gunfire are disproportionately black, which would be consistent with psychological experiments suggesting that in dangerous situations, people are more likely to shoot at black people than at white people.

The Center for Policy Equity at the University of California, Los Angeles has received a grant to compile a national database on profiling by police, which would include data on officer-involved shootings. The researchers at the center hope that their project will help police departments maintain the confidence of the communities they're tasked with protecting.

"There are some tough questions that need to be answered, and as of today, they have not been answered," said Denver Police Capt. Tracie Keesee, one of the center's founders. "For us, the database is certainly the beginning of that."

Keesee and her colleagues are asking police departments around the country to volunteer information for the project, so the data won't be exhaustive. Still, she thinks many chiefs of police will be eager to participate, especially as they look to prevent the kind of animosity that has thrown Ferguson into chaos in recent days.

"There isn't a chief that isn't watching this and saying, 'It could have been us,' " Keesee said.

Questions for police include basic ones, such as whether officers shoot more often during summer. The data could also help police recruiters who are wondering what traits they should be looking for when they hire. Senior officers also often want to know whether the training that cops get is helping them deal safely with people with mental or physical handicaps -- which has become a major part of every officer's job.

"The issue lies in how officers are being trained and what they’re being told about their obligations to protect their lives of civilians when they’re on the street," said Delores Jones-Brown, a professor at John Jay College of Criminal Justice, City University of New York, who has studied shootings by police.

She also noted that many departments have instituted systems to monitor officers' behavior for signs of stress, frustration and violence.

Ferguson police say that Darren Wilson, the officer who shot and killed Brown, had no history of disciplinary action, and it is not clear what Ferguson police could have done, if anything, to save Brown's life. Still, a national database would allow researchers to compare department policies on all of these issues over time and from one jurisdiction to another, so that law enforcement can do everything possible to prevent similar deaths in the future.