A study of YouTube videos about vaccinations found that those presenting a negative view were more likely to have unsubstantiated information in them, and also tended to be more popular. I’m not sure why anyone is surprised by this.

This is a case of self selection bias. Positive messages are already widely distributed through push media by governments and other PR programs. It would follow that that those searching for vaccination information on YouTube are more likely to be looking for other viewpoints not already well represented. Once a viewer’s negative opinion of vaccination programs is validated by a video, they’re more likely to rank the video higher and generate additional traffic by sharing the content with others. I expect a similar analysis of 911 related videos would find a similar bias towards conspiracy theories.

The study really just highlights how those holding passionate views on a topic can skew the outcome of an analysis. In this case reviewers should be careful not to assume both sides are equally likely to take the time to rank and share a video.