A daily glass of wine prolongs life--yet alcohol can cause life-threatening cancer.
What should we make of this endless barrage of conflicting claims? Observation and Experiment is an Introduction to Causal inferen.
Scientists once confidently claimed that hormone replacement therapy reduced the risk of heart disease but now they equally confidently claim it raises that risk.
Some say raising the minimum wage will decrease inequality while others say it increases unemployment.
A daily glass of wine prolongs life--yet alcohol can cause life-threatening cancer