PREAMBLE:It may help those who are unaware of what "epidemiologists" do to know that they are researchers who collect data about people and diseases and try to find patterns. This involves lots of data collection and statistical analysis usually. A simple (and early) example of what an epidemiologist does would be the first study to show that those who smoked were more likely to develope lung cancer etc. NOW FOR THE JOKE.....
There is a group of five statisticians on a train. At the next stop, five epidemiologists get on. They all seem to know each other and start chatting. It transpires that all the epidemiologists have bought a ticket, but the statisticians have only bought one between the five of them. "Why did you do that?" asks one of the epidemiologists. "Surely you're going to get caught and thrown off the train?" "Just wait and see!", smiles one of the statisticians.
As the ticket inspector is approaching to check everyone's tickets, the statisticians all go off to the nearest toilet - the inspector passes the epidemiologists and inspects all their tickets then moves on and notices that the toilet is locked. "Tickets please!", shouts the inspector. One of the statisticians pushes their ticket under the toilet door, which the inspector checks and returns under the door. Once the inspector has gone, all the statisticians return to their seats to the awe and amazement of the epidemiologists. "That's incredibly clever!" says one of the epidemiologists.
A few weeks later they all find themselves on the same train again. They sit together and start chatting once more. "We've done what you suggested", says one of the epidemiologists. "And just bought one ticket between the five of us!" "Oh really", says one of the statisticians. "we haven't bought ANY tickets this time!" The epidemiologists look at each other in amazement. "OK, one ticket between you is fine but not buying any at all is ludicrous!"
As the ticket inspector approaches the epidemiologists hurry off to the toilet. Once they're inside, the statisticians follow them. "Tickets please!" shouts one of the statisticians. The ticket appears under the door and they take it away and all bundle into a different toilet. The inspector gets to the toilet with the epidemiologists in it. "Tickets please!" he shouts. No reply. "Tickets please!" The epidemiologists admit defeat and come out of the toilet only to be thrown off the train at the next station.
THE MORAL OF THIS STORY: Epidemiologists should not attempt to use statistical methods without fully understanding the theory behind them!
*Kudos to Dave Ewart from the Imperial Cancer Research Fund, Oxford UK for this clever story.
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