NEW YORK - Economist Paul Samuelson, who won a Nobel prize for his effort to bring mathematical analysis into economics, helped shape tax policy in the Kennedy administration and wrote a textbook read by millions of college students, died yesterday. He was 94.

Samuelson, who taught for decades at Massachusetts Institute of Technology, died at his home in Belmont, Mass., the school said in a statement announcing his death.

President Obama's chief economic adviser, Lawrence Summers, is Samuelson's nephew.

In 1970, Samuelson became just the second person, and first American, to win the Nobel Memorial Prize in Economic Sciences, created in 1968 by the Central Bank of Sweden. The other Nobels have been awarded since 1901.

The award citation said that Samuelson "has done more than any other contemporary economist to raise the level of scientific analysis in economic theory."

A 1970 New York Times profile said that his mind "possesses the agility of a Nijinsky and the endurance of a cross-country runner." When he won the Nobel, he said it was "nice to be recognized for hard work."

Samuelson was a liberal and, like many of his generation, a follower of British economist John Maynard Keynes, who proposed that a nation needs an activist government that could foster low unemployment by steering tax and monetary policies, even if it meant deficit spending at times.

"In the old-fashioned laissez-faire economy, prosperity was indeed a fragile blossom," he wrote in a 1970 article for the New York Times.

"But for a modern 'mixed economy' in the post-Keyensian era, fiscal and monetary policies can definitely prevent chronic slumps, can offset automation or under-consumption, can insure that resources find paying work opportunities."

He was among a circle of JFK advisers, who also included John Kenneth Galbraith and Walter Heller, who led Kennedy to recommend the historic income tax cut that Congress eventually passed in early 1964, three months after the president was assassinated.

"A temporary reduction in tax rates on individual incomes can be a powerful weapon against recession," Samuelson had written in a report to Kennedy in early 1961.

The cut was widely credited with helping foster the 1960s economic boom.

It was Samuelson's work as an educator, in the classroom and as a textbook author, that may have been his most influential role.

College students have been reading "Economics" since the late 1940s.

It had its roots in a short text that Samuelson put together to use in his MIT classes.

It is now in its 19th edition; the more recent editions were co-written by William D. Nordhaus, of Yale.

The book has sold more than 4 million copies in more than 40 languages.

"I knew it was a good book, but what I didn't realize would be its lasting power," Samuelson said in a 1998 Associated Press interview.

He said that his aim was to make economics "understandable and enjoyable. . . . I think economics - and this is what I've tried to impart - has a tremendous amount of human interest in it."

Born in Gary, Ind., in 1915, Samuelson graduated from the University of Chicago in 1935 and received master's and doctoral degrees from Harvard. He joined the MIT faculty in 1940.

He married Marion Crawford, a fellow economist, in 1938, and credited her with helping in his early research.

She died of cancer in 1978 at age 62. In 1981, Samuelson married Risha Eckaus.

Samuelson is survived by his wife, six children and 15 grandchildren.

Funeral arrangements will be private, but MIT said that it plans to hold a public memorial service.