The United Jewish Communities' (UJC) National Jewish Population Survey 2000-01 (NJPS) was widely viewed as flawed. Still, the Jewish community held to the survey's estimate that there were 5.2 million American Jews.
But even using the same criteria as UJC did to define who is Jewish, it's more likely that there are 6 million to 6.4 million American Jews, according to a report released last week by a team of sociologists at the Steinhardt Social Research Institute at Brandeis University.
If a broader definition of Jewishness is used, the number could be as high as 7.4 million, according to Len Saxe, a Brandeis professor and head of the Steinhardt research center, who led the report.
Saxe's study suggests a larger, more diverse and less affiliated community than did the NJPS. The two surveys present very different narratives, Saxe said.
The difference, he says, can be seen in the opening chapters of Scott Shay's new book, "Getting our Groove Back: How to Energize American Jewry." Drawing on the NJPS results, the opening chapters paint American Jewry as a melting ice cube. But the U.S. Jewish population is actually growing, Saxe says.
That implies two very different motives for communal programming. One is alarmist: If the Jewish community is rapidly shrinking, then it must be saved. The other is optimistic: More potential Jews means more people to bring back to the core.
But the numbers suggest that the community, even if it is growing, has not been effective in certain areas -- penetrating a much smaller portion of the Jewish population than previously thought -- and it will take more programming to reach the underaffiliated. That also means significantly more philanthropic funding will be needed, Saxe said.
Philanthropists such as Michael Steinhardt, who funds Saxe's institute, are looking at the new numbers as a rallying call.
"What is of great concern is the fact that the institutional Jewish world is serving fewer people, less meaningfully than we thought before," Steinhardt said before the report came out.
Another recent survey conducted by sociologist Ira Sheskin comes to a similar conclusion, but Saxe's study involved a "meta-analysis" of some three-dozen government and private foundation surveys that query religion.
The meta-analysis, a painstaking process that involves not only analyzing the data but calibrating each survey to make sure they all use the same statistical language, provides a more accurate portrait than the NJPS, Saxe said.
The surveys Saxe used generally are more extensive and thorough than the NJPS and, he said, are better at finding Jews by birth and self-identity. The NJPS also missed Jews on college campuses.
But the biggest discrepancy is that most of the calls for the NJPS surveys were made during early evening hours, when many Jews in their 20s and early 30s are not home because of work or social engagements, Saxe said.
When the survey did find Jews at home, there was a greater-than-average chance that they were Orthodox, who tend not to eat out and who have familial obligations at a younger age, he said.
Especially in today's cell phone age, some young Jews may not even have land lines, giving surveyors virtually no chance of reaching them.
In all, the NJPS underestimated the total number of children by up to 30,000 per age cohort, according to the new study.
The NJPS estimates that 29 percent of Jewish children attend day school. But if there are 100,000 more children than believed, the percentage attending day schools is correspondingly lower, Saxe said in his study.
The new report also represents a challenge to the federation system, which already knew it was collecting fewer dollars from fewer donors, but now must consider that it is actually receiving money from an even smaller percentage of its donor base.
If Saxe is correct, the undercounting of Jews in their 20s means that even successful programs, such as Birthright Israel, will have to redouble their efforts.
Steinhardt made his statement several days before Feb. 6, when the Adelson Family Charitable Foundation pledged $25 million a year to birthright for the next several years.
The growing wait list for Birthright Israel trips could provide anecdotal backing for Saxe's findings, according to Jeffrey Solomon, president of the Andrea and Charles Bronfman Philanthropies. In North America, there were more birthright applicants last year than young Jews having bar and bat mitzvahs.
For the organized Jewish world, the challenge is to reach the demographic of Jews between college entry and marriage, about an 11-year period.
"Those years are especially important to identity forming, but at the same time there is very little in Jewish life that targets that age group," Solomon said. "It is time for us to play a little catch-up and see this as an enormous opportunity."
But it's not time to panic, according to Sanford Cardin, executive director of the Charles and Lynn Schusterman Family Foundation, a major funder of programs that target young Jews.
The challenge is the same whether there are 5.4 million American Jews or more than 6 million, Cardin said. While more philanthropic dollars are needed, it's up to the organized Jewish world to create excitement about Judaism that will inspire people to return to the fold, and that's not a function only of the amount of programming.
"Jewish life is not about providing services and programs," Cardin said. "It is about attracting, engaging and infusing people with a way of living that they can choose to live."
"Ultimately this isn't about creating a pot of money. This is about sparking renewed interest [in] and understanding of Jewish life by a large number of Jewish people," he said. "It's about reaching the individual. And the way that is going to work is more vital and through a network."