Quantifying the Impact of TV News Bias – Example #1

The following example represents my core method of quantifying the impact of media bias, using only program segments from the top 3 cable news networks in this particular example. The underlying “Raw Bias Index” data I am using is in fact quite coarse, so consider this an alpha trial put forth for review and discussion.

Much debate has been devoted to assessing whether there is a liberal or conservative media bias. Qualitatively, a case can be made for both, but quantifying the effective bias is a more complex endeavor.

In my recent studies of television news programming, it occurred to me that the quantity of liberal TV outlets seemed greater than conservative channels, but their “share-of-voice” may still be lesser. The true impact of a particular TV news program can only be determined by considering both bias and reach.

In order to add a viewership variable, I used the Nielsen Cable News Ratings from September 8, first calculating the average rating of the 6 largest cable news networks for the entire day. (Source: TV by the Numbers – Zap2It website. http://tvbythenumbers.zap2it.com/2011/09/09/fox-news-leads-presidential-address-viewing-among-cable-news-ratings-for-thursday-september-8-2011/103155/ )

 NOTE: “P2+”= Viewers over the age of 2.

I then calculated a “Viewership Weighting” factor for each of the post-Presidential address programs from CNN, Fox, and MSNBC that I had previously created a Raw Bias Index for (see Sept. 11 post below), and com combined them to create a “Raw Impact Index.”

Needless to say, prime time news is viewed much more extensively than its daytime cousins, hence the large viewership weighting factors. Still, one can readily see in this crude example that viewership, not the number of TV outlets, is key to determining the overall impact of news bias.


PLEASE NOTE that this is but an example, and is not meant in any way to be an accurate-or-comprehensive measure of TV news bias today.


Is this methodology simplistic? You bet. I fully expect critiques from those more experienced in media measurement and proficient with survey science. Regardless, simpler is often times better.

As always, I remain open to feedback, and encourage you to leave yours in the comments section.

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