Evidence of political bias in English-language Wikipedia articles

To quote Stephen Colbert, "reality has a well-known liberal bias."

One potential flaw that I see in this study is that I think Republican strategy has changed from a strategy of positive sentiment to a strategy of negative sentiment. I notice that Ronald Reagan rates highly here, which doesn't surprise me since Reagan is known for his "morning in America" campaign, he was optimistic to a fault.

It's not surprising to see George W Bush so low, because I think both sides have turned against George Bushes neo-conservative interventionism, and Trump, regardless of how you evaluate his policies or leadership is a negative sentiment machine. Trump is the anti-Reagen in terms of his approach, and in general I would say the Republican strategy of the past decades has been oriented around a more negative sentiment.

So yeah, maybe a different methodology is required or something that takes this into account?

How do you cover Trump in a fair way without including words that bias towards a negative sentiment? Without ever quoting him?