In this tutorial you will calculate attributable risk percent based on the relative risk problem found at http://www.youtube.com/watch?v=V5DCNOwl9IA
I get a few comments now and then that attributable risk is ONLY the top part of this equation. I tend to like to call that part of the equation "difference in risk". If it is that difficult to understand that this is a proportion measurement, which makes the difference in risk easier to understand (especially for cases where the risk of disease is small), then I am sure there are many other videos on youtube that will reaffirm your memorization of a formula.