Incredible Evidence of P Hacking in Research Studies, Demonstrated with One Chart

Hat tip to Kevin Drum for finding this:

I will let him explain the chart, it is worth understanding:

The authors collected every significant clinical study of drugs and dietary supplements for the treatment or prevention of cardiovascular disease between 1974 and 2012. Then they displayed them on a scatterplot.

Prior to 2000, researchers could do just about anything they wanted. All they had to do was run the study, collect the data, and then look to see if they could pull something positive out of it. And they did! Out of 22 studies, 13 showed significant benefits. That’s 59 percent of all studies. Pretty good!

Then, in 2000, the rules changed. Researchers were required before the study started to say what they were looking for. They couldn’t just mine the data afterward looking for anything that happened to be positive. They had to report the results they said they were going to report.

And guess what? Out of 21 studies, only two showed significant benefits. That’s 10 percent of all studies. Ugh. And one of the studies even demonstrated harm, something that had never happened before 2000

Reports for all-cause mortality were similar. Before 2000, 5 out of 24 trials showed reductions in mortality. After 2000, not a single study showed a reduction in mortality.

Note that these sensible rules for conducting a study do NOT exist for pretty much any study in any field that you see in the media.  Peer review generally does not address it.  Links to the full study in Drum's article.