The easiest way would be to talk to reporters who cover the major beats. Beat reporters generally have a good grasp of long-term trends and proportional significance, even though often they can only hint at them in the course of covering news stories. Some items would change rarely. Other items might jump around in the context hierarchy. Still others might show up once, and then vanish.
Cost is one key factor.
Every column-inch on a newspaper page, every minute of broadcast time, costs significant amounts of money. While it also would cost money to assemble and publish an online news context section, that option certainly wouldn't cost as much as printing it in the paper or putting together a broadcast segment. But perhaps more importantly, the concept of news context concerns trends and relationships . Currently, the biggest potential drawback of using the Web to present news context is access. Fewer people have access to the Web than to newspapers or broadcast media.