|"This chart indicates the probability that I am|
bleeding heavily from my index finger."
A trio of statisticians was on a train going to a conference, sitting alongside them was a trio of economists. As they chatted about this and that, the economists learnt that the statisticians only had one train ticket between the three of them.
"How do you expect to get away with that?" Asked one economist.
"No problem, we have a technique for that," came the reply.
When the conductor came along checking tickets the three statisticians all hid in a toilet. The conductor knocked on the toilet door, their one ticket was slipped underneath, punched and handed back.
"That is an impressively cunning plan!" observed the senior economist after the statisticians had returned to their seats, "I wish we'd thought of that."
Seeing the opportunity to reduce costs, for the return journey the economists bought just one ticket between them and boarded the train. Shortly afterwards, the statisticians boarded and sat next to them. They exchanged pleasantries whereupon the economists excitedly revealed that they had adopted the statisticians' technique and planned to travel using just one ticket between three.
"Jolly good," nodded the senior statistician, "though in fact we have no ticket at all this time."
"What? How can you get away with that?" gasped the economist,
"Don't worry, we have an advanced technique for that,".
Just then the conductor was sighted so the economists disappeared to the toilet with their ticket and their plan. Meanwhile, two of the statisticians went to the adjacent toilet while the third paused a moment then walked over to the economists' toilet and knocked firmly, "Tickets, please!". The ticket was slipped underneath and the third statistician joined his colleagues.
A few moments later the conductor knocked on the toilet door: the overture to a long, heated and rather embarrassing scene involving one angry conductor, three red-faced economists caught together in flagrante in a train toilet and much amusement for the rest of the train.
The lesson: make sure you understand the principles behind a statistical technique before trying to apply it.