A physicist, a chemist, and a statistician were supposed to give a guest lecture at a school.

When they arrive at the classroom, the professors see with alarm that there is a fire in the wastebasket.

The physicist says, "We must cool down the materials until their temperature is lower than the ignition temperature and then the fire will go out."

The chemist says, "No! No! We must cut off the supply of oxygen so that the fire will go out due to lack of one of the reactants." While the physicist and chemist are debating, they observe with alarm that the statistician is running around the room starting other fires.

They both scream, "What are you doing?"

To which the statistician replies, "Don't mind me, I'm just trying to get an adequate sample size."