There was once a group of Bio-statisticians and a group of Epidemiologists riding together on a train to joint meetings.
All the Epidemiologists had tickets, but the Bio-statisticians only had one ticket between them. Inquisitive by nature, the Epidemiologists asked the Bio-statisticians how they were going to get away with such a small sample of tickets when the conductor came through. The Bio-statisticians said, "Easy. We have methods for dealing with that." Later, when the conductor came to punch tickets, all the Bio-statisticians slipped quietly into the bathroom. When the conductor knocked on the door, the head Bio-statistician slipped their one ticket under the door thoroughly fooling the layman conductor. After the joint meetings were over, the Bio-statisticians and the Epidemiologists again found themselves on the same train. Always quick to catch on, the Epidemiologists had purchased one ticket between them. The Bio-statisticians (always on the cutting edge) had purchased NO tickets for the trip home. Confused, the Epidemiologists asked the Bio-statisticians "We understand how your methods worked when you had one ticket, but how can you possibly get away with no tickets?" "Easy," replied the Bio-statisticians smugly, "we have different methods for dealing with that situation." Later, when the conductor was in the next car, all the Epidemiologists trotted off to the bathroom with their one ticket and all the Bio-statisticians packed into the other bathroom. Shortly, the head Bio-statistician crept over to where the Epidemiologists were hiding and knocked authoritatively on the door. As they had been instructed, the Epidemiologists slipped their one ticket under the door. The head Bio-statistician took the Epidemiologists' one and only ticket and returned triumphantly to the Bio-statistician group. Of course, the Epidemiologists were subsequently discovered and publicly humiliated.
MORAL OF THE STORY: Do not use statistical methods unless you understand the principles behind them.
