[tonixie]

There's an interesting blog post about something similar:

https://slatestarcodex.com/2014/04/28/the-control-group-is-o...

Basically it boils down to the fact that studies & statistics used are still very, very, prone to human bias.

[lostmyoldone]

Which can as well be seen an argument why statistics are necessary, as even with them we are stuck with a lot of bias. Imagine where we would be if we didn't have statistics at all!