What is 2 + 2?
If you're a normal person, the answer is four.
If you're a mathematician, the answer is either four, ten, or eleven depending on what base you compute in.
If you are a statistician, there is a 68% chance the answer lies between 3.95 and 4.05, a 95% chance that the answer lies somewhere between 3.9 and 4.1, and a 99.7% chance the answer lies between 3.85 and 4.15. This of course assumes a mean answer of 4 and a standard deviation of .05.