The equal numbers I am referring to are the FOX journalists who pursue the stories for the hard news coverage, not opinion, but hard news like that presented at 6 in the evening, behind the faces seen on the screen.
Those invisible journalists whose charge is story selection are themselves selected based on their political bias. FOX prefers an equal number of liberals and conservatives in these positions. The reason for this is that if story selection is done by a group that is predominantly conservative or predominately liberal potential stories go missed ... a byproduct of this process is FOX's boring but lucrative balance in news coverage.
This story via Forbes from the 2008 election comports with FOX's balance...
ABC, CBS, NBC coverage as a group
==Obama 68% positive, 32% negative / McCain 36% positive, 64% negative
However for FOX,
==Obama 36% positive, 64% negative / McCain 40% positive, 60% negative
Within the numbers one can see reflected the liberal argument that FOX was hard on Obama ... arguably biased.
But also within the numbers is reflected FOX's argument that Fox itself was hard on both Obama and McCain. And is that not the proper role of a watch dog press? To be hard on both all of governance? Recall that FOX manages this via a balanced sort of digging for dirt behind the scenes.
The fact is that FOX only appears bias when contrasted against the true bias of the big three networks, while being nearly unbiased in regard to the pursuit of news coverage.