NEW YORK — As debate over the validity of the 2000-2001 National Jewish Population Survey is rekindled, the United Jewish Communities is nearing a decision to discontinue the once-a-decade practice of counting the American Jewish people.

When UJC found in its 2000-2001 NJPS that the American Jewish population stood at roughly 5.2 million, the number was widely scrutinized. Opponents claimed the UJC has used a flawed methodology for counting Jews, and many were dismayed that it showed a 300,000 decrease in Jews from the UJC’s 1990 population survey.

After two years of debating the accuracy of the 2000-2001 study, the discussion seemed to wane as Jewish communal professionals decided it had value even if it wasn’t perfect. But the 2006 American Jewish Yearbook, which came out Dec. 18, claims the U.S. Jewish population is roughly 6.4 million.

University of Miami professor Ira Sheskin and University of Connecticut professor Arnold Dashefsky arrived at the 6.4 million figure from surveys conducted by local Jewish communities.

Sheskin admits that their survey was fundamentally flawed. In counting individual communities, the two professors were bound to overcount by several hundred thousand people because of Jewish “snowbirds” who have two residences. Also, they had to rely on estimates from smaller communities, which can be inexact.

But the 5.2 million figure from the NJPS just didn’t make sense, according to Sheskin, who helped conduct the NJPS and has conducted Jewish population surveys in 35 individual communities.

When larger cities such as New York and Chicago conducted individual population studies over the same period, they showed little or no population drop. And over the past decade, the Jewish population in cities such as San Francisco and Las Vegas has exploded, Sheskin said.

In any case, a more in-depth survey set to be released in coming weeks says that even the 6.4 million figure may be low.

Len Saxe, director of Brandeis University’s Cohen Center for Modern Jewish Studies, is about to publish the findings of a meta-survey of the Jewish population. The scientific analysis and calibration of three dozen vaunted population studies, such as the American National Elections Study and the General Social Survey, was conducted within three years of 2001 and includes questions about religion.

“We believe that the number of Jews by religion is close to 6 million,” Saxe said, “and there is an additional population of individuals who are Jews by some other criterion — that could be between 10 percent and 20 percent more. The bottom line is that while I don’t endorse the methodology Sheskin used, the fact is that our conclusions are similar.”

Clarifying the NJPS findings is important, Saxe said, because the methodology not only gave a low estimate of the size of the Jewish population but drew an inaccurate portrait of who is Jewish.

The NJPS relied on early evening cold calls to households that were presumed to be Jewish. But because Orthodox Jews keep kosher and tend to have homebound children, they typically don’t eat out on weekdays, meaning there was a greater chance that those calling Jewish households would end up talking to Orthodox families, Saxe said.

Therefore, when the surveyors asked questions about religious practice, they found a higher rate of observance than among a more representative audience, Saxe said.

There are several reasons that crunching the numbers is important, according to Jonathan Sarna, a professor of Jewish history at Brandeis University.

A recent study by Sergio DellaPergola of The Jewish People Planning Policy Institute in Jerusalem showed that Israel’s Jewish population had surpassed the American Jewish population — at least based on the NJPS estimate.

The fluidity of estimates about the American Jewish community in some ways has become a contest for “bragging rights” about which is the largest Jewish community in the world, Sarna said.

In fact, the press release sent out earlier this month by the American Jewish Committee, which publishes the American Jewish Yearbook, said its estimate of 6.4 million American Jews “indicates that American Jewry remains the largest Jewish community in the world, surpassing the Jewish population of Israel.”

There is concern as well about whether the American Jewish community is shrinking, especially relative to the U.S. Muslim community. In the past, when religious groups such as the Episcopalians and the Presbyterians lost numbers, they also lost political clout.

But Sarna says the biggest question raised by the varying studies is “How do you count Jews?”

There’s disagreement over whether such surveys should count self-identifying Jews, anyone who lives with a Jew or is somehow associated with Jews, or only Jews who are both self-identifying and who associate with some Jewish institution.

If the 2001 NJPS had counted only the last category, Sarna said, its estimate of the Jewish population would have been closer to 4 million.

The UJC is on the verge of deciding whether to conduct another national survey in 2010. A decision is expected by the end of the month.

“Over the past several months we have embarked on a complete analysis and redesign and plan for our research foundation,” said Rabbi Lou Feldstein, the UJC’s associate vice president of research and analysis. “One piece is a discussion around the NJPS.”

Though no final decision has been made, to replicate the NJPS as it was conducted in 2000 “would be both very expensive and may not serve the needs of the federation in terms of moving forward,” said Barry Swartz, the UJC’s senior vice president of federation services.

The UJC is considering conducting more targeted studies, perhaps looking at different aspects of philanthropy, studying how population sprawl has affected service delivery within the Jewish community or taking a look at specific age groups such as the baby boomers, he said.

The UJC spent millions of dollars on the 2001 survey, and “if we were to follow the same exact regimen, that number would grow exponentially,” Swartz said. “We want to make sure we get value in return.”