The suburban Boston university’s Steinhardt Social Research Institute is estimating that there are some 6.5 million people in the United States who are either Jewish by religion or who self-identify as Jewish. The figure represents a 20 percent increase in the number of Jews since 1990.

The numbers were drawn from a synthesis of data from more than 150 nationwide surveys conducted by the US government and other agencies, as well as from national polling organizations.

They refute information gathered in the last National Jewish Population Survey, a census-like study that had been conducted every decade by the Jewish federation system before being discontinued this year. The final survey showed that between 1990 and 2000-01, the population dropped from 5.5 million to 5.2 million.

A parallel polling by Brandeis of 1,400 Jews revealed that more than 80 percent of respondents who indicated that they are Jewish identify as such by religion, while the rest identify as Jewish by some other criteria.

According to the study, 1.27 million Jews who identify by religion are younger than 18. The Steinhardt center has not yet broken down other demographic data from the survey, but will roll out more information about demographics, socioeconomic status and other areas over the course of the next year, the center’s director, Len Saxe, told JTA.