text: Mo Ibrahim prize for African leadership: No winner 
   
   Mo Ibrahim said only exceptional leaders will get the prize 
   
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   There is no winner this year for the world's most valuable individual prize - the Mo Ibrahim prize for good governance in Africa. 
   
   The $5m (£3.2m) prize is supposed to be awarded each year to a democratically elected leader who governed well, raised living standards and then voluntarily left office. 
   
   The panel said no candidate had met all of the criteria - as in 2009 and 2010. 
   
   Last year, Cape Verde President Pedro Verona Pires won the prize. 
   
   He led the fight against Portuguese colonialism, introduced multi-party politics and was praised for raising living standards. 
   
   The $5m prize is spread over 10 years and is followed by $200,000 a year for life. 
   
   'No compromise' 
   
   Announcing the decision, Mr Ibrahim said: "You make your bed, you have to lie on it. If we said we're going to have a prize for exceptional leadership, we have to stick to that. We are not going to compromise." 
   
   "We are not just in the business of positive messages - we would lose our credibility," the AFP news agency quotes him as saying. 
   
   "The prize committee reviewed a number of candidates but none met all of the criteria needed to win the prize," said committee member Salim Ahmed Salim. 
   
   The two other winners in the six years since the prize was launched were Botswana's President Festus Mogae and Mozambique's Joaquim Chissano. 
   
   Earlier this month, Mr Ibrahim's foundation announced a special $1m award to Archbishop Desmond Tutu for "speaking truth to power". 
   
   The London-based body called the cleric "one of Africa's great voices for justice, freedom, democracy and responsible, responsive government". 
   
   Sudan-born telecoms entrepreneur Mr Ibrahim says the good governance prize is needed because many leaders of sub-Saharan African countries come from poor backgrounds and are tempted to hang on to power for fear that poverty awaits them when they leave office. ||||| The Royal Swedish Academy of Sciences cited the two economists for "the theory of stable allocations and the practice of market design." 
   
   The Nobel Memorial Prize in Economic Sciences was the last of the 2012 Nobel awards to be announced. 
   
   It's not technically a Nobel Prize, because unlike the five other awards it wasn't established in the will of Alfred Nobel, a Swedish industrialist also known for inventing dynamite. 
   
   The economics prize was created by the Swedish central bank in Nobel's memory in 1968, and has been handed out with the other prizes ever since. Each award is worth 8 million Swedish kronor, or about $1.2 million. ||||| Two American economists won the Nobel Prize in economics Monday for their research into how to match different actors in given markets, such as job seekers with employers and patients with donated kidneys. David Wessel has details on Lunch Break. Photo: AP. 
   
   Two Americans won the Nobel Prize in economics Monday for research that has improved the way people are matched with limited resources, such as patients with donated organs or students with their preferred high schools. 
   
   Enlarge Image Close Reuters Lloyd Shapley, above, and Alvin Roth won the prize in economics for separate bodies of work that have helped kidney patients and high-school applicants. 
   
   Alvin Roth, a Harvard University professor who is moving to Stanford University, and Lloyd Shapley of the University of California Los Angeles were honored "for the theory of stable allocations and the practice of market design," the Royal Swedish Academy of Sciences said. 
   
   Their research focuses on how to fairly and efficiently match people with things—be they employers, schools or donated kidneys—when pricing isn't involved. Their work led to systems used by school districts in New York City, Boston and other cities to place students in high schools; by hospitals to match donated kidneys with patients; and by a program that assigns recent medical-school graduates to hospitals for residency programs. 
   
   Messrs. Shapley and Roth worked independently, rather than together. 
   
   The academy pointed to Mr. Shapley's research, starting in the 1950s, that was highly theoretical—he initially examined how spouses select one other—and later was used by Mr. Roth to address real-life situations. 
   
   Real Time Economics Alvin Roth and Lloyd Shapley were lauded for their research on how to match different agents in markets, such as job seekers with employers. Find out more about their work in this Real Time Econ post. 
   
   "Now we are able to see the fruits of this 50-year quest, if you wish, and these techniques—initially very much mathematical—are now directly affecting peoples' lives," said Tayfun Sonmez, a Boston College economist. Mr. Sonmez, who also has done research on matching kidney donors and patients, said the systems developed by Messrs. Shapley and Roth have made it easier for families to find others for kidney exchanges. "We can use some of these insights to optimally organize these exchanges so that we can save as many lives as possible," he said. 
   
   Two American economists have won the Nobel Prize in economics for their work in researching market design and putting practical applications in use. Harvard's Alvin Roth and Lloyd Shapley of UCLA were honored. Video: Associated Press. 
   
   The academy said the pair's combined work "has generated a flourishing field of research and improved the performance of many markets." The award, officially called the Sveriges Riksbank Prize in Economic Sciences in Memory of Alfred Nobel, carries a $1.2 million prize. 
   
   Mr. Shapley, 89 years old and a professor emeritus at UCLA, was honored for 1960s-era research, conducted with the late David Gale, that theorized how men and women could be matched for marriage. A "stable" match occurred when each side's preferences were met. The academy said Mr. Shapley's algorithm ensured "stable matching" and served to "limit agents' motives for manipulating the matching process." 
   
   Winners & Their Work Read more about the 2012 laureates. View Graphics Nobel Prize Winners See which academic institutions and countries have had the most winners. View Graphics 
   
   Mr. Roth, 60, later used that theoretical research to address real-world problems. Starting in the 1980s, he first examined the residency system used to assign medical-school graduates to hospitals and determined that the system led to "stable matches." But not for all. The system couldn't accommodate doctor couples who wanted to be placed in the same region. Mr. Roth redesigned the system to take into account such requests when placing residents. 
   
   Mr. Roth helped redesign New York City's process for assigning students to high schools in 2004. Under the old system, students would list their top five preferred schools. Schools, in turn, were more likely to admit students who ranked them as their first choice. After three rounds of selections, remaining students were assigned through an administrative process, the Academy said. Some 30,000 students a year were assigned to schools for which they had expressed no preference, the academy said in a description of Mr. Roth's work. Mr. Roth designed a new system, based on Mr. Shapley's and Mr. Gale's initial algorithm, that addressed those issues. In the first year, the number of students assigned to schools they hadn't requested dropped by 90%. 
   
   Getty Images Alvin Roth 
   
   In a phone interview broadcast during a news conference in Sweden, Mr. Roth joked, "When I go to class this morning, my students will pay more attention." 
   
   He said in a separate interview that one outcome of his research is that schools are responsive to families' preferences. "School places are scarce resources. What's a good place for one child may differ from child to child," Mr. Roth said. The algorithms developed by Mr. Roth and his colleagues let schools use the information provided by parents on which schools would best suit their children. "It would be a shame not to use that information well," he said. 
   
   In a statement released by UCLA, Mr. Shapley's sons, Peter and Christopher Shapley, said, "We know he is tremendously thankful that his life's work is being recognized with such a prestigious award and grateful for the many congratulations expressed by colleagues and friends." 
   
   Write to Josh Mitchell at joshua.mitchell@dowjones.com
target: – Americans Alvin Roth and Peter Shapley have won the Nobel prize for economics on the strength of their work matching players in a wide range of markets, the Wall Street Journal reports. "For example, students have to be matched with schools, and donors of human organs with patients in need of a transplant. How can such matching be accomplished as efficiently as possible?" asks the Swedish Academy in charge of the awards. "The prize rewards two scholars who have answered these questions on a journey from abstract theory on stable allocations to practical design of market institutions." The prize is the last of the 2012 Nobels to be awarded, the AP notes. In other major prize news, this year's winner of the Mo Ibrahim prize for good governance in Africa is... nobody. Just as in 2009 and 2010, no candidate qualified for the world's biggest individual prize, at $5 million. The prize is intended for a leader who's elected democratically, boosts living standards, and leaves office voluntarily, the BBC notes. "You make your bed, you have to lie on it. If we said we're going to have a prize for exceptional leadership, we have to stick to that. We are not going to compromise," said Ibrahim.