there is also political correctness bias as well. as in, some research cannot be easily questioned as intent can be misrepresented by those who want the research to stand or are too sensitive about the subject. The example given in the article was a perfect demonstration. Things that tend to reinforce what we believe or want others to believe we believe are easy to support.

Still as for this door too door study, the Wilder effect is a good example of bias you get when asking people sensitive questions