You may or may not have heard the tagline that "90% of guns in Mexico's drug war are being smuggled in from the US ZOMGGUNRUNNERS!!!111!1". Well StratFor (an open-source commercial intelligence service for businesses and non-governmental organizations) ran the numbers and...
Meh, not so much...
30,000 firearms seized by Mexican authorities
7,200 firearms submitted by Mexican authorities to the US Bureau of Alcohol, Tobacco, Firearms, and Explosives for trace (24% of total seized)
4000 ATF firearms traces successfully completed (55.6% of trace requests, 13% of total seized)
3480 firearms traced to US sources (87% of successful traces, a fraction less than 50% of total trace requests, and only 11.6% of total seized
(Source: June, 2009 US General Accountability Office report to Congress, as cited in StratFor's article)RTWT
. You can't fix the problem if you're working from wrong assumptions, and the article does a good job of examining the issues and debunking the myths.
On my bookshelf is a charming little text entitled How to Lie with Statistics
I have the 1954 edition; the link goes to a 1993 edition, but I suspect that little has changed in the ways that the unscrupulous manipulate data to get the results they want, and use those results to, in turn, manipulate the public. Illicitly redefining your statistical base, as in the case at hand, is only one of the more commonplace.
Or, put more simply, there is a technical term for those individuals who are throwing out fraudulent numbers to effectively lie to the American people. That term is "bullshit artist