Angus Deaton, a Princeton professor renowned for his meticulousness, has won the 2015 Nobel Prize for economics. PHOTOGRAPH BY JEWEL SAMAD / AFP / GETTY

Back in the late nineteen-nineties, I was working on a piece about the stock market and consumer spending, both of which were surging. Looking for a respected economist to provide a pithy quote backing up my thesis that rising stock prices were driving individual spending decisions, and that the stock-market bubble was likely to end badly, I called Angus Deaton, the Scottish-born Princeton University professor who has just been awarded this year’s Nobel Prize for economics.

I chose Deaton because, from my days as an economics student, I was familiar with some of his academic work. In 1980, with John Muellbauer, who is now a professor at the University of Oxford, he co-authored a book called “Economics and Consumer Behavior,” which, even today, I sometimes consult to check how much my brain has atrophied. In this instance, though, I had called the wrong man. Instead of a pithy quote, I received a lengthy lecture on the difficulty of estimating the so-called wealth effect, the perils of drawing conclusions about individuals from aggregate statistics, the lopsided nature of wealth distribution in the United States, and much else besides. As I recall, Deaton concluded by saying that he would need to see a good deal more data before reaching any conclusions about how the stock market was impacting the rest of the economy.

That was typical of Deaton, who is now sixty-nine. Renowned for his meticulousness, he believes that the world is a complicated place and that reducing it to simple theories is almost always dangerous. In his long career, he has often played the role of a skeptic challenging fashionable models, from the “rational expectations” approach to macroeconomics to the use of randomized testing in assessing policy interventions in developing countries. However, Deaton is also an optimist—about his own field of study and the evolution of mankind generally.

Deaton developed a reputation early in his career as a formidable theoretician and econometrician. Among his achievements was creating, with Muellbauer, a system for testing how the demand for individual goods varies with prices and incomes, which was widely adopted by other economists. But he has spent much of the past thirty-five years studying poor countries, where reliable statistics are hard to come by.

His most influential work involved showing how to employ household surveys conducted in developing countries, a method many economists had previously regarded as unreliable. In a series of studies during the eighties and nineties, Deaton championed the use of these detailed questionnaires, rather than G.D.P. statistics, to measure poverty and welfare and to evaluate policy actions. By combining the surveys with some carefully developed economic theory and statistical methods, he demonstrated how to assess living standards and many other things, including the causes of malnutrition and the extent of sexual discrimination within poor families. And in directing attention toward behavior in individual households instead of national trends and overarching theories, he helped revive the field of development economics, which is now largely concerned with the micro rather than macro.

Deaton has also ventured into popular writing, where he has focused on the big picture. “Life is better now than at almost any time in history,” he wrote in a 2013 book titled “The Great Escape: Health, Wealth, and the Origins of Inequality.” “More people are richer and fewer people live in dire poverty. Lives are longer and parents no longer routinely watch a quarter of their children die.”

In that book, Deaton acknowledged that serious problems, such as raging diseases and rising inequality, remain. But his over-all message was an upbeat one, and, from that perspective, the Nobel award was well-timed. Last week, the World Bank predicted that this year, for the first time on record, the number of people living in extreme poverty will fall below a billion and suggested that, by 2030, the phenomenon could be eradicated. Deaton has long had a close relationship with the World Bank and its research department. In a press conference after the Nobel announcement, he said, “My measurements tend to show that things are getting better, but there is a lot of work still to be done.”

Deaton hasn’t shied away from controversy during his career. Thirty years ago, when many American macroeconomists were embracing the theory of rational expectations and using it to criticize traditional Keynesian policy remedies, he pointed out that the data on consumer spending didn’t support some of the new theory’s implications. More recently, he has emerged as a harsh critic of economic aid from rich countries, like the United States. “I have come to believe that most external aid is doing more harm than good,” he wrote in “The Great Escape.” “If it is undermining countries’ chance to grow—as I believe it is—there is no argument for continuing it on the grounds that ‘we must do something.’ The something that we should do is stop.” Deaton also questioned the widespread presumption that rising inequality is always a bad thing. In developing countries, he wrote, “inequality is often a consequence of progress.”

Over the years, the Swedes have often honored conservative economists who believe in the free market and who criticize well-meaning government programs. More recently, the prize has also gone to scholars who query market forces, such as George Akerlof and Robert Shiller. Deaton’s work can be cited by both sides of the markets-versus-intervention debate. (In a 2014 post, I took issue with some of his approach to inequality.) But inside the field of economics, few question his credentials or his commitment to scholarship.

If you want to read more about Deaton’s work, the Nobel committee has provided two useful surveys, one designed for general readers and another that is more technical. Like his mentor at the University of Cambridge, the late Richard Stone, Deaton is an empiricist but also a systematizer, who is primarily interested in the right way to analyze things. “I’ve always wanted to be like him,” Deaton told Binyamin Appelbaum, of the Times. “I think putting numbers together into a coherent framework always seemed to me to be what really matters.”

During and after the Second World War, Stone, who won the economics Nobel in 1984, helped invent national income accounting. Deaton’s contribution is perhaps not quite on that level, but, at a time when economists often get a bad rap (sometimes justifiably so), his work conveys an important message: if you are clear about the theoretical assumptions you are making, and you are careful—very careful—about how you interpret the data, economics can provide a powerful tool with which to analyze and improve the world.