Lies, damned lies, and statistics

"There are three kinds of lies: lies, damned lies, and statistics." - Benjamin Disraeli

Reading this article on misuse of statistics reminds me of the discussion four of us had on our journey to airport from the flooded city of Hue in Vietnam. One key point that I would really like to point out is:

False causality

When a statistical test shows a correlation between A and B, there are usually four possibilities:

1. A causes B.
2. B causes A.
3. A and B are both caused by a third factor, C.
4. The observed correlation was due purely to chance.