Bill and Melinda Gates publish their annual letter

GETTING KILLED in a video game, receiving unfair treatment from a teacher, seeing a relative go to jail: the teenagers taking part in Chicago’s Becoming a Man (BAM) initiative admit to a variety of frustrations, some trivial, some tragic, that can stir their anger. The initiative, which teaches young men how to regulate their emotions, aims to lower crime rates and improve graduation rates. Recently one BAM group invited an unusual guest into their counselling circle: Bill Gates, the second-richest man in the world. So what pushes his buttons?

Mr Gates answers that question in his latest annual letter, written with his wife Melinda, describing the work of the $50bn charitable foundation they oversee. He admits to being “pretty harsh” with his parents as a child and “tough” on people at Microsoft. (“Over the decades I’ve mellowed out on that,” he says.) He also remembers “getting mad” at a meeting when he learned that polio cases were increasing.

In his first letter ten years ago, Mr Gates argued that a “maniacal focus on drawing in the best talent and measuring results” would make a difference in the foundation’s fields of interest: global health, development and American education. In health, he feels vindicated. The progress in research, vaccine delivery and statistical monitoring to which they have contributed is “more miraculous than the digital revolution,” Mr Gates says.

But in education, results are less striking: test scores have been harder to budge. Even in health, the eradication of polio has proven maddeningly elusive. In 2003 he thought the disease would be gone in a couple of years. But it lingers.

What explains this uneven impact? Partly, a paradox of progress: the more successful development efforts become, the less effective they look. Now that polio has been eliminated from countries like India, only the hardest cases remain, such as Afghanistan. The unevenness also reflects underlying differences in the problems the foundation tackles.

Such problems can be roughly divided into three categories (following a taxonomy by Lant Pritchett of Harvard and Michael Woolcock of the World Bank). Some require the exercise of ingenuity and discretion by small teams (eg, inventing a new vaccine); some demand the programmatic mobilisation of legions of people (immunisation drives). Others require both.

Improving education falls into this third, difficult category. It is not a problem that a small team of brilliant people can crack. Nor can a good education be delivered, like a vaccine, by following a strict protocol to the letter. Instead it requires legions of teachers to respond thoughtfully and conscientiously to pupils’ needs. Mr Gates left his BAM circle wishing every classroom could emulate its intimacy and respectfulness. But that is hard to bottle.

Some problems that seem to belong to one category end up in another. Mr and Mrs Gates first thought the fight against malaria would require a breakthrough vaccine. To their surprise, the world has instead made headway by rolling out bed nets, a programmatic not technical solution.

An opposite example is sanitation. Removing the dirt and danger of human waste would not seem to require much innovation. Effective sewers and toilets have been around for over a century. But installing them is no longer feasible in many poor countries, Mr Gates argues, where cities are too big and water too scarce. Instead he wants to reinvent the toilet. In Beijing last year, he reviewed the latest self-contained models that, in effect, are their own sewage treatment plant, killing pathogens on site.

“If you want to improve the world,” Mr Gates once wrote, “you need something to be mad about.” The letter contains many candidates, including the neglected causes of climate change (“trucks, cement and cow farts”) and the shortage of data on women’s unpaid work. But does he worry that his passions might distort his foundation’s priorities? “I might be the last person people would accuse of setting strategies based on non-numeric emotions,” he says. The BAM circle touched his heart, his wife writes. But she’s also careful to cite a University of Chicago study showing it cut arrests for violent crime by almost half.