The Bill Gates foundation had a similar incident to the kidney study. After studies revealed that the best performing schools were small schools, they spent a huge amount of money helping school boards divide large schools into multiple smaller ones.
A few years later someone realized this was simply a statistical artifact that small schools will be have a higher variance in their scores due to a smaller population. After a while the Gates foundation stopped supporting the practice and apparently eventually acknowledged the math mistake.
Details can be found in the second half of this NBC article.
