In some islands north of Scotland, if head lice (头虱) left their host, he became sick and feverish. Therefore, sick people had lice put in their hair intentionally. There was a method in their madness: As soon as the lice had settled in again, the patient improved. The story explains the confusion of cause and effect. If the lice leave the sick host, it is because he has a fever and they simply get hot feet, and when the fever breaks, they return. Such false causality (假因果关系) misleads us every day.
Consider the headline: "Fact: Women Who Use Shampoo XYZ Every Day Have Stronger Hair." It says very little -- least of all, that the shampoo makes your hair stronger. It might simply be the other way round: women with strong hair tend to use Shampoo XYZ -- and perhaps that's because it says "especially for thick hair" on the bottle.
Another example: Scientists found that long periods in the hospital did harm to patients. But, clearly, patients who are dismissed immediately are healthier than those who must stay on for treatment.
Recently I read that students get better grades at school if their homes contain many books. This study was surely a shot in the arm for booksellers, but it was also false causality. This simple truth is that educated parents tend to value their children's education more than uneducated ones do, and they often have more books at home. In short, a dust-covered copy War and Peace alone isn't going to influence anyone's grades; what counts is parents' education levels, as well as their genes.
There was also the supposed relationship between the birth rate and the numbers of stork (鹳) pairs in Germany. Both were in decline, and if you plot (描绘) them on a graph (曲线图)，the two lines of development from 1965 to 1987 appeared almost the same. Does this mean the storks actually bring babies? Obviously not. This was a purely accidental connection.
In conclusion: Connection is not causality. Take a closer look at linked events: Sometimes what is presented as the cause turns out to be the effect, or just the other way round, and sometimes there is no link at all - just like with storks and babies.
