Methodology behind ABC News' Gun Violence Tracker

Deaths and injuries will be measured over weeks, months and years.

This report is a part of "Rethinking Gun Violence," an ABC News series examining the level of gun violence in the U.S. -- and what can be done about it.

ABC News has launched an interactive tool to track reported gun-related incidents in the United States as part of its initiative "Rethinking Gun Violence."

The tracker, a partnership with the Gun Violence Archive, is a novel presentation designed to give our audience the most up-to-date figures on gun deaths and gun injuries in the U.S.

Aggregate recent data on gun violence incidents in the U.S. is notoriously difficult to come by, with some thousands of law enforcement agencies reporting and a significant lag in data from the FBI and the U.S. Centers for Disease Control and Prevention (CDC).

The Gun Violence Archive, on the other hand, an independent non-profit, has been tracking gun-related incidents in the U.S. since 2013 on a near real-time basis through a variety of other sources including law enforcement, media and other government entities .

These reports include the number of victims, the location of the incident and the most recent description of what happened.

Further details about GVA's definitions and methodology are listed on its methodology page. For instance, GVA says its numbers "are based on provable reported individual incidents" and that the numbers may change from time to time based on updated information.

ABC News' Gun Violence Tracker employs the Gun Violence Archive's data and shows the number of gun-related deaths and injuries recorded over the past week, year and five years. The numbers will be updated every evening Eastern time.

Watch ABC News Live on Mondays at 3 p.m. to hear more about gun violence from experts during roundtable discussions.

Deaths include homicides, accidental discharges, and suicides associated with police standoffs and murder-suicides.

There will be a three-day lag between the time of a reported gun incident and the time it appears on the tracking widget to ensure data accuracy.

For the weekly graphs, the reader will see the past seven days of data starting three days prior to the current date (i.e. on Oct. 25, you would see Oct. 16-22).

For the other two sets of graphs (past year and five years), there will likely be noticeable dips at the end because we employ month-to-date and year-to-date data for the prior 12 months and five years respectively.

For those graphs, the month- and year-to-date figures shown on the graphs will increase until the 3rd of the following month, where the current month/year data point will start increasing daily again from 0.

The Gun Violence Archive's data does have some lag when it comes to real-time reporting on certain incidents as well.

For instance, reported suicide incidents are collected quarterly and annually by GVA "due to differing distribution methods by government agencies."

Gun deaths and injuries that are unreported until after the incident takes place also lead to a lag in the data.