NEW YORK — An influential study of U.S. Jews, released Wednesday after a delay that threatened its credibility, provides evidence of a smaller but in some ways more engaged Jewish community in America.
The National Jewish Population Survey concluded that the number of Jews has decreased 5 percent to 5.2 million in the past decade, as a low birth rate combined with slightly rising levels of intermarriage.
However, the study also found increased enrollment in Jewish day schools and some observance of holiday rituals among even the least-engaged Jews.
The survey, conducted every 10 years, shapes how millions of dollars are spent to keep Judaism alive in the United States. But the latest version is about two years late and its conclusions and methodology are already being contested.
“There was a lot of tension around every aspect of this study,” said Egon Mayer, a Brooklyn College sociologist and technical adviser to the study who disagreed with its approach.
Field workers had trouble convincing enough people to participate in the lengthy interview. About 4,500 eventually responded, although not all were asked every question.
Preliminary findings were released last October, then abruptly retracted after the agency overseeing the project, United Jewish Communities, discovered that an outside firm which conducted field work had lost some data used to determine who would be interviewed.
The agency asked independent experts to examine the impact of the missing data, along with the survey’s overall methodology and response rates. Those experts determined the report was sound, said Bernard Shapiro, the former head of McGill University, who led the investigation.
“I am convinced that the months taken to review the study have confirmed it contains a tremendous amount of important and reliable information,” Shapiro wrote in the report’s preamble.
The margin of error varies according to groups of questions, but never reaches higher than plus or minus 3 percentage points, researchers said.
The $6 million study had been promoted as the most extensive portrait ever of American Jews. It is at the center of a debate over whether leaders should reach out to Jews on the fringes of religious life or strengthen support for those already active.
Among the most contentious issues was defining who is Jewish. Researchers included people who either said they were Jewish, or were born to a Jewish parent or raised Jewish and did not convert to another monotheistic religion such as Christianity.
The margin of error on the 5.2 million total population figure was plus or minus 2 percentage points. Mayer is among those who believe the definition used was too narrow, and probably caused an undercount.
The most anticipated finding was the rate of intermarriage.
Researchers determined that the figure was 43 percent from 1991-1995 and 47 percent from 1996-2001.
However, those statistics are not directly comparable to the 52 percent rate reported in 1990, which was based on a broader definition of who is Jewish, including Jews who were raised with another faith.
Critics said that approach exaggerated the intermarriage trend. Researchers for this latest study recalculated the earlier statistic using their narrower definition and said the intermarriage rate in 1990 was 43 percent.
Steven Cohen, a Hebrew University sociologist and consultant to the survey who said the 52 percent figure was inaccurate, said either statistic for 1990 would have “led to the same policy” — spending on programs that build Jewish identity.
The Orthodox Union, which claims 1,000 North American Orthodox congregations, said the report pointed to a continuing “assimilation crisis” — meaning that Jews are leaving their faith.
Zale Newman, a national youth director for the union, said programs were needed to make young people feel “they are a critical part of the Jewish people.”
“We must get to them before we lose them,” he said.
The study found that Jewish women, on average, have no more than two children, fewer than women in the general population and too low to replace losses in the Jewish community. And the median age for Jews is 42, five years older than a decade ago.
Only one-third of children of interfaith couples are being raised Jewish, according to the report.