SCOTT SIMON, host:
The greatest sporting event in the world starts next Friday. The World Cup opens in Johannesburg and runs for a month, before a World Cup winner emerges. Football - we say soccer here - scholars say that in recent years a lot of international games have been decided by penalty kicks.
WEEKEND EDITION's Math Guy, Keith Devlin, joins us from Stanford.
Keith, thanks very much for being with us.
KEITH DEVLIN: Hi, Scott. Good to be here as usual.
SIMON: More international games ending this way?
DEVLIN: It certainly seems to be. And that certainly happened with last World Cup when there was an exciting shootout between France and Italy.
DEVLIN: And Italy got more penalty kicks.
SIMON: So what can the shooter do to improve his odds?
DEVLIN: Yeah. Well, what piqued my interest in this as a mathematician was a study that was done quite recently within the last few months at Liverpool's John Moores University. They confirmed that the best chance for a kicker is to aim for one of the two callers high and to one side. They found out that the speed has to be between 56 and 65 miles and hour. If it's faster than that, then the kicker is going to lose accuracy. If it's slower than 56 miles an hour, then the goalie has a chance to catch it.
SIMON: Of course, if the goalkeeper knows that the odds favor putting it in one of those corners, the goalkeeper will do his best to be in one of those corners, won't he?
DEVLIN: The goalie has to start somewhere in the middle.
DEVLIN: But another interesting study says if the goalie is just between three and five inches off the center point, the kicker is going to kick towards the area that's slightly larger. And so if the goalie is three or five inches to one side but then dives towards the other side, his chances of saving it are going to be higher, so...
SIMON: So the goalie can fake him out by - you know how they love to jump around and twitch their hips, right?
(Soundbite of laughter)
DEVLIN: I think youre talking about goalies psyching them out. The most effective one on this one blew me away when I read about it.
DEVLIN: The color of the jersey that the goalkeeper wears is a huge factor. This, by the way, was a study done at the University of Chichester in England. If the keeper wears a red jersey, only 54 percent of penalties will succeed. It goes up to 69 percent if it's yellow. If the keeper wears a blue jersey, 72 percent will go in. And the worst thing that the keeper could do is wear a green jersey because then 75 percent of penalty kicks will go in.
The theory, by the way, is that red is a dominant color. It signifies danger and anger, and so that would attract the kicker's attention. As we all know, if youre looking at something...
DEVLIN: ...you'll probably head in that direction, so the goalie's job is to get the kicker to look at him. Then the chances are going to be higher because he will be able to save the kick.
SIMON: So is there a mathematical answer to why the Brazilians are year in and year out the best soccer players in the world?
(Soundbite of laughter)
DEVLIN: The mathematics in all of these studies, they can help, they can give you a little bit of an edge. But all of sports really comes down to people who just spend thousands of hours practicing. Brazil is one of those soccer nations.
SIMON: WEEKEND EDITION's Math Guy, Keith Devlin, speaking to us from Stanford, California.
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