Simpson's paradox - Wikipedia

Simpson's paradox for quantitative data: a positive trend ( , ) appears for two separate groups, whereas a negative trend ( ) appears when the groups are combined. Visualization of Simpson's paradox on data resembling real-world variability indicates that risk of misjudgment of true causal relationship can be hard to spot. Simpson's paradox is a phenomenon in probability and statistics in which a

[dynamicsoar]

生物でもたまにあるやつ（たとえば種内の傾向は右上がりだけど種間では右下がり、とか）

[Nean]

こういうネタは本家版のほうがたいがいなが～い。