My gut feel from what I saw is that outright fraud is rare, but bias seeping into the study is common. Researchers invest a huge amount of effort into a study, they really want the hypothesis to be true. A lot of studies have steps that are pretty susceptible to bias, like maybe you’re classifying results and there’s a bit of a judgement call there. It’s human nature to make biased decisions in these situations, and make enough of these biased decisions, and statistically insignificant results become statistically significant.
Some people might not see a difference between bias and fraud, but I personally do. I think of fraud as a very intentional deception, straight up falsifying numbers in a conscious attempt to deceive. While I see bias as more, you’ve got a borderline case, and you view it in the light you want to see it in, even somewhat unconsciously. Like the difference between unconscious racial bias, and overt hateful racism.
I think the best approach to combatting this is to spend a lot less of the overall $$ in science on novel research, and a lot more on attempting to independently reproduce results. Papers should be seen as meaningless until their results can be independently reproduced, and universities/colleges should reward reproduction studies as much as novel research. It’s kind of crazy that the system almost completely lacks these checks and balances right now - peer review is more like an editor, it’s just a very different thing than reproduction.
Bishop here is suggesting a data sleuthing approach to root out fraudsters, but I dunno if that’d be effective, as I think the main issue is subtle but pervasive bias seeping into studies by most researchers, vs. a smaller number of heavy fraudsters. Independent reproduction of results, while expensive, is the only effective approach I can think of to combat this.