What is exactly "This sounds like barn door statistics!"?
The answer from above wiki link is so much fun it must be worth entering here on the ELU site;
The name is from a joke about a shifty Texan who shoots at a barn, then paints a target centered on the tightest cluster of hits, then claims to be a sharpshooter!
It refers the tendency of some , to infer trends in statistics where none exist.