Not a bad site, but you cannot use it scientifically.
When calculating bias we are not just looking at political bias, but also how factual the information is and if they provide links to credible, verifiable sources. Therefore, the yellow dot may indicate political bias or how factual a source is, or in many cases, both.
This discredits basically the entire thing. You're measuring two entirely different things. It would be like stating a certain number could mean age, penis lenght or both. You have no idea whether someone is just really old or hung like a horse, or both.
Further, we have placed a voting poll on each page for readers to vote on the bias of the source. This is similar to how a movie sites such as IMDB or Rotten Tomatoes rate their movies.
But is horrible as a format to check for a factual bias. The risk of people giving a site a bad rating because they simply don't like it is present and therefor makes the rating not trustworthy.
They also do not explain what they consider 'liberal' or 'right-wing'. Is is what the checker considers left-wing? But are there different checkers with different opinions on what constitutes left or right-wing? Are there certain 'buzz words' they have categorized? What are these? Do they just tick a box when there's a word, or does it matter how often it returns? For one category, they even admit that it's not trustworthy and do not explain how pages get this rating.
Political Affiliation: How strongly does the source endorse a particular political ideology? In other words how extreme are their views. (This can be rather subjective)
Lastly, they do not actually state a sample-size nor check for significance, so their conclusion is, again, scientifically not usable.
