The young system: decisions without tears

Press, 28 March 1979, Page 16

The young system: decisions without tears

You are driving with your family, and there’s still a long way to go; it’s nearly lunchtime and everyone is looking forward to the perfect pub. You can’t decide about the first one, so you drive on to the next, and the next, and finally it’s a quarter-to-two and you stop at a thoroughly unprepossessing inn because otherwise you may have to go without lunch altogether. There may be some recrimination about “why didn’t we go back to that lovely Queen Anne one,” but, on a long journey, people simply don’t ever back-track. It is interesting that there exists a system which produces the best chances of avoiding disappointment in situations of just this

sort. The system is also very simple and I find it surprising that it has not. long ago become part of the folklore. The system is this: Have a good look at the first pub, and then continue your journey, looking at each successive pub until you find one that seems better than the first. That’s where you have your lunch. If, by illchance, the first pub happened to be the best, then you will just have to reject pub after pub until you take the last one you find before closing time. Let us try out the System on the very simple case of a deserted countryside which happens to have only three roadside pubs in the hour’s drive that could be spent looking for an eating-place.

One is the Best (A), one is Middling (B) and the other the Worst (C). They may be strung along the round in exactly six ways, which are equally likely.

The System will work as shown below: Order of pubs System selects C—B—A B C—A—B A B—A—C A B—C—A A A—C—B B A—B—C C So the system produces the Best three times out of six, and only produces the

Worst once out of six times. Now compare this result with just picking the first pub that turns up. This produces the Best only

once out of three times, but it also has an exactly equal chance of producing the Worst one. So the System halves the chances of eating at the Worst pub and nearly doubles the chances of eating at the Best. If there happen to be four pubs strung along the lunchtime stretch of road, they could occur in twenty-

four different equally possible orders; readers can amuse themselves by filling in a table like the one above. The System will ensure a fair chance of finding the Best pub. If there are as many as 10 pubs to choose from, then they could be distributed along the road in 3,628,800 different ways. It can be calculated that, with these 10 pubs, the System will produce the very best one 28 times out of 100, which is nearly three times better than simply choosing the first that presents itself. The System will produce one or other of the two Best Pubs 48 times out of 100, and it will only produce the very Worst one about 1 in 100 times. In my family the Young

System has been in use for years, and it has contributed much to our tempers on the road. We only break the System when the first pub looks so good that we all agree that “it’s an opportunity not to be missed.” Even without this proviso, the System also guarantees the best chances in a number of other practical situations which have the common characteristic that observing and holding back increases knowledge but only at the cost of reducing the scope of the unavoidable subsequent decision. They must all share the following general features: (1) There is an unknown number of unknown opportunities. (2) One and only one must be selected.

(3) Each opportunity is presented in turn and, if rejected, will not be presented again. (4) A rough scale of values allows all the presented opportunities to be placed in an order of merit. (5) The last opportunity, if and when presented, is announced as such and must be accepted. The system prescribes the optimum amount of waiting and seeing, during a limited number of opportunities. It teaches us that waiting and seeing is essential — but a surprisingly small amount of it. 1 suspect that many shrewd practical people apply the System instinctively, for example, in business decisions.

By PIERRE YOUNG, who is deputy engineeringdirector of Rolls-Royce and a Fellow of the Royal Society. The drawing illustrates the worst case of his three-choice example.