Pedro Gargantilla Updated: Save Send news by mail electrónicoTu name *
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The skies of Europe, Asia and Africa were witnesses of exception of human barbarity during the Second World War , due to the prominence that they gained the war planes.
During the early years, the type of aircraft that more low presented between the allies were bombers. The reasons seemed obvious, it was a matter of apparatus, huge in size, slow and with a trajectory very predictable , which made them especially vulnerable to the action of the anti-aircraft guns.
there had both edges , on the one hand was the replacement of the aircraft, the production was very slow and expensive and, for another, human lives, since in these planes the crew was around nine people, very upper to the one-seater or two-seater aircraft fighter.
Scientists helping pilots
The first measure adopted was to strengthen the armor of the bombers, to make them more resistant to enemy fire and to the fighters teutons . But, what part of the plane had to be strengthened? You could not prop up around the fuselage as it would increase both the weight which would reduce their benefits and would lose effectiveness.
it Was a priority to choose the areas of the plane more susceptible to impacts that give rise to losses . For this reason, after each mission is reviewed thoroughly the impacts received in each of the planes and how many bombers had been shot down.
In the beginning it was assumed that the areas of the aircraft with the highest number of impacts were the fragile areas of the aircraft and that, in principle, should be strengthened . An initial analysis detected a higher concentration in the wings, in the tail rudder and the main body of the fuselage, while the nose and in the area between the wings –the one for the engine and the cabin – the number of impacts was much smaller.
The shielding of the strong points
Before you continue with the project, the army requested the collaboration of a group of math experts from the University of Columbia of New York. There were figures as prominent as W Allen Wallis, Frederick Mosteller, Jacob Wolfowitz or Leonard Jimmie Savage .
But the key character of this story was Abraham Wald (1902-1950), a scientist who fled Vienna because of its status as a jew. It was he who developed the sequential analysis , the method that substantially improved the control of industrial quality.
Wald showed that, sometimes, what is obvious is not the right thing . He defended the hypothesis that if the planes that came back had fewer impacts in certain locations of the plane, of what might be expected, was because maybe the planes made in those areas had been demolished, since they were the most fragile of the device. In other words, it proposed to strengthen the areas of the plane where there was no impact.
The jewish scientist was on the basis that there were no planes lost without impacts and calculated the probabilities of being shot down in function of the number of blasts received.
In this way, estimated in a fifteen percent likelihood of being downed by a single shot , but in function of the geography of the plane in the crash could rise up to thirty-nine percent -the most vulnerable areas – or descend to the two-percent -areas more peripheral, such as the wings-.
In honor of this mathematician a jew, it was decided to baptize in his name of a statistical test-parametric–test Wald – that is used to test the true value of a parameter based on the estimate of the sample.
Paradoxes of fate, this statistic that did so much for the pilots, died when she was forty-eight years ago in a plane crash while on his way to India to give a lecture.
Pedro Gargantilla is a internist in the Hospital of El Escorial (Madrid), and author of several popular books