Sentiment Analysis is a tool developed by Newstin to indicate the overall tone of an article i.e., whether it has a positive, negative or neutral feel to it. For example, an article about an oil spillage at sea would most likely contain negative wording due to the effects of the incident. Our Sentiment-o-Meter provides readers with an indication of the tone of an article without reading it. Red represents negative tone, green positive and grey is for neutral tone: The higher the scale of the colour (from bottom to top), the greater the degree of the given sentiment.
If you go to the webpage you can see on the right side the search terms and the color bars. Pres. Obama has quite a bit or red. See here. This is a stupid attempt at ranking news stories by "sentiment" not by content. I wouldn't bother with them since they are a UK based company (Registered as Newstin a.s.).