Media bias is studied diligently at schools of journalism, and by several independent watchdog groups from various parts of the political spectrum.
Media bias has a long history.
The broadcast media has been used as a mechanism for propaganda from its earliest days. The fledgling BBC Radio News attempted to sabotage this strike by broadcasting reports of the workers breaking the strike in many areas, reports which were largely fictitious. Liberal media bias is said to exist mainly because most journalists are liberal in their political views. Such a uniformity of political opinion among journalists may tend to to give rise to a tendency to cover or not cover particular stories, or to cover them with a particular slant. Conservative media bias is said to exist mainly because the mass media are owned by a small number of very large diversified media corporations.