Dr. Janet L. Norwood gives testimony in 1987, during her tenure as the head of the Bureau of Labor Statistics. She died at age 91 in Austin. (James K.W. Atherton/The Washington Post)

Janet L. Norwood, an economist who became the first woman to lead the Bureau of Labor Statistics, an office she sought to insulate from partisanship as it measured the nation’s economic health, died March 27 at a senior-living community in Austin. She was 91.

The cause was complications from Alzheimer’s disease, said her husband, Bernard Norwood.

Dr. Norwood served from 1979 to 1991 as commissioner of labor statistics, a job whose significance far surpasses the number-crunching suggested by its title. The bureau’s monthly employment reports — and the good or bad tidings they contain — rank among the most awaited, closely watched and politically fraught functions of regular government business.

Dr. Norwood was nominated to her first four-year term by President Jimmy Carter, a Democrat, and was retained for two more terms by his Republican successor, Ronald Reagan. When she stepped down, she had, the New York Times reported, a “near-legendary reputation for nonpartisanship.”

As commissioner, she oversaw an agency with an annual budget of $300 million and 2,700 employees collecting and analyzing data on employment, unemployment, wages and prices. The bureau uses its data to formulate, among other indicators, the consumer price index tracking how much shoppers pay for goods and services.

Outside the bureau, such information helps determine cost-of-living allowances and the distribution of federal aid. Politicians frequently point to the official labor statistics, or their supposed flaws, to highlight the president’s economic successes or failings.

Dr. Norwood’s most public duties included her monthly testimony about the most recent jobs report before the Joint Economic Committee of Congress. Lawmakers began holding those sessions in 1971, after the Nixon administration became frustrated by bad news coming from the bureau and ended its news conferences with reporters.

“There was a clear feeling on the part of the White House,” Dr. Norwood told the Times in 1984, “that the bureau should be emphasizing employment rather than unemployment.”

Dr. Norwood trekked to Capitol Hill 137 times and described her repartee with legislators as “something like a fencing match.” She was rarely, if ever, enticed to venture beyond her bureau’s findings or to make predictions. Then-U.S. Rep. David R. Obey (D-Wis.) remarked during her final session that she had been “the most difficult witness to lead.”

“I find it a stimulating challenge,” Dr. Norwood told the Times in 1982. “There are always a variety of innovative senators and representatives who raise questions that I have to be very careful to answer in a completely objective framework. But the joint committee provides an open place where both political parties can play the game and ask any question they want and get a straight answer.”

During Dr. Norwood’s tenure, the bureau tracked dramatic economic changes — including the decline of manufacturing and the rise of service industries — and revised the calculation of the consumer price index.

Critics during her tenure and years later have pointed to what they regard as the bureau’s overemphasis on unemployment and insufficient attention to workers who are underemployed or have abandoned their job searches and are therefore no longer officially considered unemployed.

“The link between the unemployment rate and economic hardship is not so great as it used to be,” Dr. Norwood said in 1986.

Janet Sonia Lippe was born in Newark, N.J., on Dec. 11, 1923. She graduated in 1945 from the New Jersey College for Women, now called Douglass Residential College of Rutgers University, and four years later received a PhD in economics from the Fletcher School at Tufts University in Massachusetts.

Dr. Norwood quipped that she was “out of the labor force” while raising her children. She joined the Bureau of Labor Statistics in 1963 as a junior economist with an early specialization in international economics. She studied matters including Burmese labor law and Japanese wages before rising through the agency’s ranks.

After stepping down as commissioner, she served on an advisory committee on unemployment compensation and did research for organizations including the Urban Institute.

Dr. Norwood was a longtime Montgomery County resident and member of the Cosmos Club in Washington, a social organization that was founded in 1878 and first admitted women 110 years later. In 1995, she became its first female president.

Survivors include her husband of 71 years, Bernard Norwood of Austin; two sons, Stephen H. Norwood of Oklahoma City and Peter C. Norwood of Los Altos, Calif.; and three grandchildren.

“You can’t have a democratic society,” Dr. Norwood observed when she left office, “without having a good data base.”