I just learnt a very important lesson that will serve as a mantra during my statistical analysis for my thesis.
“Ice cream does not make people kill each other!”
A researcher found a correlation between ice cream sales and homicides, which in simple terms would mean that as soon as people start eating ice cream they’ll go on a killing spree, or that after a killer struck, s/he goes on a ice cream binge.
Luckily, this not true. It is a classic example of partial correlation. What you need to find is the third variable that is missing from the equation. In the example fom above – weather. When do people eat ice cream? And when do people spend a lot of their time outside? Summertime. A does not cause B, or the opposite, you need to find variable C.
I will nurture this little lesson dearly.