The information provided on this site is merely a compilation of data found across multiple government sourced publications and websites.
Those websites and publications include The Disaster Center (which sources data from the FBI), FBI, and even U.S. states' Uniform Crime Report (UCR) data.
It's important to note that this data is sometimes incomplete and will be noted in the source table breakdown for each chart (if possible).
In certain instances where entire country data (United States) is not provided for a particular report from the FBI (or accompanying website), Check Your Gun Stats may aggregate each individual state (as well as DC) to get the entire country's data for that particular report. This tally is only done if all 50 states and DC have data (in some instances partial data is used which can causes inaccuracies in the data).
Crime statistics are fluid figures. Being that cases can be ongoing for years, a data point for one year may increase (or even decrease) over the years. This can cause discrepancies in data across sites (even on the same site from year to year). An example might be a 2004 Murder Rate report for Maryland (strictly an example, data not real). In 2004's report the murder rate is cited as 500. However, in 2005 it might list 2004's data and say 504 murders. This is because the original murder case may not have been closed...and hence the statistics aren't affected until a year (or even more) out.
Your usage of the data is your responsibility and is not the responsibility of Check Your Gun Stats or its owner (Stephen Paul Adams).