It’s growing or it’s shrinking. It’s aging or it’s not. The different streams are gaining or they aren’t. There is one thing everyone agrees on when it comes to demographic numbers that define the Jewish community.

They are hard to find-and expensive to produce.

“For institutions, the way I describe it is that the ball is in their court and they have to adapt and change in order to become relevant to the next generation,” said Leonard Saxe, director of the Cohen Center for Modern Jewish Studies at Brandeis University. “The market is there. There’s this hunger, this desire to be part of this thing we call klal Israel, the Jewish people. They just have to figure out how to do it.”

But just how big is that market? The question has fascinated and frustrated Jewish demographers since the last National Jewish Population Study was finished in 2001 and there’s little sign that it will be replicated soon. Since then most numbers have come from local studies.

According to Jewishdatabank.org, which keeps track of federation-sponsored surveys, nearly 50 such community efforts have been undertaken since the NJPS and some have been in the Midwest. Chicago and the Quad Cities in Iowa each conducted one in 2010. Louisville did one five years ago while Detroit updated a 2005 study just last year. Nashville did one in 2002. Meanwhile Ohio has been a hotbed of information with Cleveland, Cincinnati, Columbus and Youngstown all doing studies in the last decade. Other cities have been less eager. Kansas City and Oklahoma City haven’t done studies since the 1980s. Omaha and Memphis last studied their populations in the 1970s. The only listing for Des Moines dates to the Eisenhower Administration. No listing exists at all for 16 states.

Saxe said one difficulty is census data not including religion, making it hard to weigh data when doing studies.

“That’s the first problem,” he said. “The second problem is that Jews because they are a minority, about 2 percent of the population, are more difficult to find than Catholics or Protestants who are much more numerous.”

The third issue is the complexity of Jewish identity itself.

There are some people, it depends on how you ask the question, who consider themselves Jewish but do not consider themselves religious,” he said. “They are secular. They are cultural but they are Jewish nevertheless.”

St. Louis last conducted a study in 1995, whcih estimated that 60,000 Jews lived in the St. Louis area. Barry Rosenberg, President and CEO of the Jewish Federation of St. Louis admits numbers aren’t easy to find.

“In a modest-sized community like St. Louis, it’s hard to get fine data as to where people live,” he said. “The question is how much value comes at a very, very expensive price.”

He said population surveys can run to as much as a quarter million dollars to conduct, a significant sum in hard economic times.

“The second is how impactful will that data be? How much will it drive decision-making? How will it affect policy?” said Rosenberg. “We’d all like to know but the question is will it have that kind of value in relationship to the cost.”

Rosenberg said the Federation continues to look at alternative strategies to gain information but notes that the Jewish community knows enough fundamentals about itself to understand the basics, such as supporting the elderly in an aging community.

“We don’t need a population study to tell us that’s a priority,” he said.

Ira Sheskin, professor of geography and Director of the Jewish Demography Project at the University of Miami, admits it can be tough to understand how to use the data.

“One of the reasons the national study is not being repeated is that people discovered that you can’t make decisions on a local level based on national data because the national data may not apply,” he said.

But he said that’s precisely why local studies are so important.

“They come back and say, ‘Well, that costs a lot of money,'” he said. “Yes it does, but it costs a lot more money to put in a building and find out it’s in the wrong location or you are offering the wrong things from it or that you didn’t need a building.”