The cause was cardiopulmonary arrest, said a niece, Eda F. Shapiro. She said the family had not immediately announced the death because of concerns over a long-running legal dispute in Washington over Miss Orshansky's estate. Miss Orshansky was buried a day after her death in Mount Lebanon Cemetery in Glendale, Queens, Ms. Shapiro said.
Miss Orshansky, whose parents had known poverty in Ukraine, worked for the Social Security Administration from 1958 until she retired in 1982. She was "one of a respected but mostly invisible cadre of women research professionals based at S.S.A. and other government agencies during the postwar years," the historian Alice O'Connor wrote in "Poverty Knowledge," a 2001 history of poverty research.
"These women," Ms. O'Connor wrote, "found job opportunities in federal government and other 'applied' endeavors when university jobs were largely closed off to them, although within government they were often clustered in research bureaus focusing on such traditional 'women's' concerns as social welfare, female labor force participation, families and children, and home economics. That experience as a career government statistician, a far cry from systems analysis, was what gave Orshansky the wholly unexpected designation as author of the government's official poverty line."
In 1963 and 1964, Miss Orshansky conducted the research that would become the basis of the poverty thresholds. She used the economy food plan -- the cheapest of four "nutritionally adequate" food plans developed by the Department of Agriculture -- and multiplied the dollar costs by roughly three to come up with a minimum cost-of-living estimate. (A household food consumption survey by the Agriculture Department had shown that, in 1955, families of three or more people spent about one-third of their after-tax cash income on food.)
Miss Orshansky devised more than 120 poverty thresholds, adjusting her calculations for family size and composition and rural-urban differences. She published her research in a seminal 1965 article in The Social Security Bulletin.
President Lyndon B. Johnson had declared a War on Poverty, but there was no official definition of the problem at the time. In May 1965, the Office of Economic Opportunity, the federal agency charged with carrying out the antipoverty effort, adopted the "Orshansky index" as the yardstick to measure poverty.
It was a use that Miss Orshansky herself had never intended. "Orshansky developed the index as a research tool, not an instrument of policy of a criterion for determining eligibility for anti-poverty programs," the historian Michael B. Katz wrote in "The Undeserving Poor," a 1989 history of antipoverty efforts.
The federal poverty guideline -- $9,800 for a single person and $20,000 for a family of four in 2006 -- has long been criticized as understating the true extent of poverty. It also seems outdated. Food today makes up a much smaller proportion of household expenses than it did in the 1960s; the costs of housing, transportation, child care and health care have risen far more sharply.
In 1995, a panel of the National Academy of Sciences urged several changes in calculating poverty, but no major changes have occurred, in part because they would have the politically unpopular effect of increasing the poverty rate, probably by a couple of percentage points, which would require an expansion of benefits.
Miss Orshansky, a lifelong liberal Democrat, expressed sympathy with the criticisms of the poverty line. "The best that can be said of the measure," she once wrote, "is that at a time when it seemed useful, it was there."
Miss Orshansky was born Jan. 9, 1915, the third of six daughters of Samuel and Fannie Orshansky, Jewish immigrants who settled in the Bronx after leaving Ukraine. She graduated from Hunter College High School in Manhattan in 1931 and from Hunter College in 1935, with a degree in mathematics and statistics.
Miss Orshansky did graduate work in economics and statistics in Washington. In 1939, she became a research clerk with the federal Children's Bureau, doing statistical analyses of child health, growth and nutrition. In 1942, as a statistician for the New York City Department of Health, she helped develop a survey on the incidence and treatment of pneumonia. Beginning in 1945, she spent 13 years at the Agriculture Department, collecting and analyzing records on household spending and food consumption.
In the 1960s, at the request of the Justice Department, she testified at hearings that led to the elimination of poll taxes, which had been used to keep black Americans from voting. She said that a poll tax of $2, for example, would be enough to cost many poor families an entire day's meals.
Miss Orshansky received honors from the Social Security Administration, the American Statistical Association and the American Political Science Association. For most of her career, she lived in an apartment on the waterfront in Washington. She traveled extensively and loved to cook.
In 2002, The Washington Post reported on a legal struggle over Miss Orshansky's care, which had begun after she was hospitalized in the fall of 2001. A niece, Jane M. Pollack, had taken Miss Orshansky to New York, but a judge in Washington, who had named a legal guardian for Miss Orshansky, tried to compel her to return to Washington, arguing that her family had not demonstrated that they could adequately care for her.
On Aug. 15, 2002, the District of Columbia Court of Appeals ruled that the judge had abused her authority and ignored Miss Orshansky's wishes to live with her family in New York. The appeals court also canceled the appointment of the guardian. Other legal issues remain unresolved, said her niece Ms. Shapiro of Manhattan.
In addition to several nieces, Miss Orshansky is survived by a sister, Sarah Pollack of Manhattan.
By SEWELL CHAN, April 17, 2007 © The New York Times Company