Not very often, if at all, because liberals in the media leave the impression that gun control is a key to the murder rate. They have every right to believe that. But that does not include the right to filter out facts that go against their theory.
One widespread example of media bias is reporting the arguments of one side and the emotions of the other side. Usually both sides have both arguments and emotions but the liberal media often report only the liberal arguments.
In the recent Supreme Court decision upholding affirmative action at the University of Michigan Law School, a front-page news story in the New York Times reported the arguments used in Justice Sandra Day O'Connor's majority opinion but simply dismissed the dissenting arguments of Justice Clarence Thomas by saying that he "took as his text not the briefs but his own life story."
Those who doubt the existence of media bias should go on the Internet to find Justice Thomas' opinion ( www.supremecourtus.gov ) and read it for themselves to see if there is anything anywhere in it that bears any resemblance whatever to the characterization used by the New York Times to keep its readers from knowing what his arguments were.
The New York Times has every right to be in favor of affirmative action. But that is very different from preventing its readers from knowing what the arguments are against it -- especially in what is presented as a "news" story, rather than a front-page editorial. Media bias is still alive and well at the New York Times, and so apparently is the spirit of Jayson Blair.