It's a great xkcd but it's really wrong on one count, it's not some outside media/popular force compelling scientists to investigate something. Most of the time

It's a great xkcd but it's really wrong on one count, it's not some outside media/popular force compelling scientists to investigate something. Most of the time, researchers are looking to prove something they "know" to be true. They truly believe that jelly beans cause acne, they just need to prove it. When they get a negative result, they simply don't believe it. Something must have gone wrong, obviously, because jelly beans obviously cause acne, so maybe it's a color thing? Ah hah it's the green ones, now that we have our results we can construct other metrics to support this correct data! Eventually if we (the public) are lucky someone else in the field will disagree and run the trial again, which is how you get the alt text.