Simpson's Paradox

I found Simpson's paradox fascinating the first time I came across it in a course by
Daphne Koller,
The paradox (loosely) states the following,
Say we are trying to decide whether a drug is beneficial in curing a disease in a population where males and females are equally represented. We are given statistics that 57.5% of patients who took the drug are cured whereas only 50% of the patients who did not take the drug are cured. This seems to suggest that the drug is beneficial in general. But, we are also told that 70% of the male patients who took the drug are cured whereas 80% of males who did not take the drug are cured. Among females, 20% who took the drug are cured and 40% who did not take the drug are cured. These numbers look surprising! Right? Thus despite the apparently harmful effect of the drug on both men and women, the overall effect of the drug seems beneficial.

How is this possible?

I'll explain the result in my next post! Stay tuned...