The discussion on bias automatically brings the question of what is the truth? To argue that a newspaper favors a particular topic or person (i.e. It is biased), one has to know what is the {\it expected} number of times that a topic or person should be mentioned.

Although politics are a multi-facet subject and politicians many times become popular on the media due to characteristics other than their performance as a politician, we decided to evaluate our proposed method entirely from the angle of ``collaborativeness''. We define the ``collaborativeness'' of a politician (in our case a senator) as the number of times this politician has collaborated with other senators (absolute collaborativeness) and the rate of each of those collaborations (weighted collaborativeness). The true level of collaboration of a senator is given by the concept of co-sponsorships. In the US Senate, bills can be introduced by any of the senators and others generally demonstrate their support by co-signing the introduced bill. Furthermore, according to Campbell \cite{campbell1982cosponsoring}, co-sponsorship are actively sought by the bill proponent because they can use the number of co-sponsorships on speeches as an indication of broad support for the bill's idea. Given this market for co-sponsorships, one could be inclined to say that they take place quite often, but Fowler \cite{fowler2006connecting} has observed that the average legislator cosponsors only 2-3\% of the bills---meaning they are quite selective.

The data related to the co-sponsorship from the 103$^{\text{th}}$ US Senate was collected by the New York Times Congress API\footnote{http://developer.nytimes.com/docs/read/congress\_api}. Both senator's name and number of co-sponsorship in the bill were available there. We collected data for 104 senators which is 4 over the normal 100. The additional names are: Jeffrey Chiesa (1), Republican, in replacement to Frank Lautenberg (died), then replaced by Democrat Cory Booker (2); William Cowan (3), Democrat, interim of John Kerry (Secretary of State), then replaced by Democrat Edward Markey (4).

One of the challenges when it comes to doing analysis of newspapers bias relates to the data collected. Most newspapers are not keen on giving their data for analysis and request us not to use Web crawlers to collect data either. Therefore, we decided to abandon our initial thought of using Web crawlers in lieu of using information from Google search queries because Google has already done the parsing of the pages on each site and can provide us with just the count we need.