33% of interviewees believed a non-existing conspiracy theory

…as measured by the 2016 Chapman University Survey Of American Fears […] 30% about Obama’s birth certificate, and 33% about the North Dakota crash. This last one is especially interesting because there was no unusual crash in North Dakota when the survey was written. The researchers included it as a placebo option to see if people would endorse a conspiracy theory that didn’t exist. 33% of them did.

Source: Bush Did North Dakota | Slate Star Codex