Political Variables

Political party identification and conservative/liberal orientation are based on the distributions of the population over the years 2008 to 2015. For a description of the data and models, see Methodology Section.

Where are Alaska and Hawaii?

A majority of the surveys limit their sampling frames to the continental United States. Estimates for Alaska and Hawaii are, therefore, not included in our major national models. Future work can explore differences between surveys that include these states and those that do not and develop separate estimates for these states.

What are the "Low" and "High" values?

The "Low" and "High" values represent the 95% credible intervals associated with each estimate. Credible intervals based on Bayesian analysis are similar in concept to confidence intervals reported in single surveys, which are often described in terms of the "margin of error." Both the credible intervals and the margin of error represent the degree of certainty associated with the estimate. They differ in how they are calculated and how they are interpreted. For example, if one estimates the proportion of US adults who are Jewish to be 1.8% with a margin of error of 0.03, one would add or subtract this amount times some critical value to describe the variability in the estimate. For a 95% Confidence Interval, one would multiply the margin of error by 1.96, yielding a distribution that ranges from 1.74% at the lower end to 1.86% at the upper end. The confidence interval is based on the assumption that any sample drawn using the same sampling methods as those used in the particular survey of interest will yield a somewhat different estimate and somewhat different range on that estimate. A 95% confidence interval means that were one to repeat the sampling, one can expect 95% of the interval estimates would include the population parameter in this range. In the Bayesian analysis, we are synthesizing data across repeated samples directly and are, therefore, reporting on results of the repeated samples themselves, rather than reporting on the assumption of repeated samples. For our national estimates, across all of the repeated independent samples, the estimated proportion of US adults who identify as Jewish is 1.8%, with a 95% credible interval of 1.71% to 1.82%. This means that there is a 95% probability, based on the data and prior information, that the true population proportion of US adults who identify their religion is Jewish is between this interval. For the demographic data, we have only included the point estimate on the maps. For the full range of credible values associated with all of the detailed population estimates, see the detailed tables.

Why are some areas so large while others are a single county?

For the surveys in our data synthesis, the lowest level of geography for which there is reliable data across the largest number of surveys is county. There are more than 3,000 individual counties in the United States. While larger counties have sample sizes that can be reliably estimated, many smaller counties have too few cases to be estimated individually. For a few states -- Delaware, Maine, Montana, New Hampshire, North Dakota, South Dakota, Vermont, and West Virginia -- this results in all counties within the state having to be combined. As we continue to develop models and add new sources of data, including data targeted to specific regions, it may be possible to do custom analyses within these states to obtain estimates for specific counties of interest.

Do you have data on other religious groups?

We collect data for all religiously defined groups represented in the surveys that are part of the data synthesis. This includes Protestant (denominations and subgroups within, including evangelical and mainline), Catholic, Mormon, and Muslim, as well as no religion and other religions. With the exception of Catholicism, there is much variability across surveys in how other religious groups are represented across the surveys. For example, some surveys might not distinguish a general category of "Mormon" from the more specific LDS Church, or might include only on general categories such as "Methodist", "Baptist", or "Lutheran" for Protestant denominations and ignore the differences between the specific denomination within those broad categories. We have not yet explored the variability or developed population models for these other groups. We have, however, begun to explore and model the large group who identify with no religion, which also varies across surveys in how it is assessed (atheist, agnostic, nothing in particular, etc.).

Do you only have data on religion?

A number of other variables are collected as part of the data synthesis project. The Jewish population models currently include only those variables related to model-based estimation of the population as a whole. These are male/female, age, educational attainment, and race/ethnicity, as well as geographic variables of state, counties, and metropolitan areas. Other variables collected as part of the project include: marital status, income, whether the respondent was born in the US, whether they own/rent their home, length of time in residence (home/city), political orientation, political affiliation, religious service attendance, religious orientation (fundamentalist/evangelical), the importance of religion, household size, number of adults and children in the household, and community type (urban/suburban/rural; city, suburb, etc.). Surveys vary in which demographic data are included so sample sizes and numbers of samples vary for each analysis. A number of survey "meta-data" are recorded as well, such as date and day of the week the survey was conducted, incentives, and number of calls required to complete the survey. The dataset also includes methodological characteristics of all of the surveys included in the synthesis, such as response rates, length of time in the field, survey shop, sampling methods, survey purpose, and questions used to assess religious affiliation.

How do current estimates differ from previous years?

A major change in the current release is the extrapolation of our model-based estimate of the proportion of adults who identify their religion as Jewish to the total Jewish population. Past work focused solely on providing an overall adjustment at the national level. In the present release, additional sources of data were used to provide total population estimates for all geographic areas (counties and metropolitan areas). Local Jewish population surveys were used, where available, for the proportion of children in each area and the proportion of adults who do not identify as Jewish by religion. Where no local survey data was available, data from the most recent national Jewish population survey conducted by Pew Research Center was used. The local estimates of these groups vary in terms of reliability. We've decided to include them as they represent the best available information at this time. Users should be aware, however, that these are estimates that vary in reliability and potential bias. Future work will focus on more systematic data collection across regions to improve estimation of these groups. We will also be exploring the number of children in the household across surveys as an additional source of information.

It should be noted, especially for small geographic areas, any differences between estimates published in past work represent changes and improvements in methodology probably more than they do changes in the distribution of the Jewish population within these areas.

Why do other published estimates differ from yours?

Across county and metropolitan areas, estimates derived from the data synthesis vary in terms of how similar they are to population counts derived from other sources, such as those reported in the American Jewish Yearbook (AJYB). There are many places, small and large, where the data synthesis yields similar estimates as the yearbook. For example, AJYP reports a total Jewish population of 2,700 people in the Fort Collins, Colorado and Cheyenne, Wyoming area. Our model-based estimate for this area is a total population of 2,500. For counties in South Carolina, west of Columbia, the AJYB reports a total of 3,210 people. Our model-based estimate for this area is 3,300. The AJYB reports a total of 400 people in all of North Dakota, which is identical to our estimate of the number of Jewish adults (450). Our total population increases to 800 applying adjustments for children and adults who might not identify as Jewish by religion.

In more populated areas, such as Pittsburgh, Pennsylvania, the data synthesis estimate for Allegheny county of 45,000 is nearly identical to the 2002 Jewish Population Study of Pittsburgh, which estimated 44,900. The AJYB reports a somewhat lower estimate of 42,000. In the Phoenix area, our model-based estimate is similar (~87,000) to the estimate reported in the AJYB (~84,000).

For as many areas where the model-based estimates are similar to those reported in the AJYB, there are just as many or more where the estimates are disparate. The disparities are indicative of potential biases in local reporting and is the primary purpose of establishing a baseline population profile derived from independent sources of data through a data synthesis such as this. It might also be that our population models "fit" some areas of the country better than others and more work needs to be done to improve our models in these areas. The data synthesis has several features that distinguish it from other sources such as those reported in the AJYB that enable researchers to examine potential sources of bias directly. In particular, factors such as source bias, time bias, error estimation, and undercoverage which are inherent in the yearbook estimates, are, to some extent, obviated through data synthesis. See our detailed research note "Why Do These Estimates Differ from Other Published Estimates" here for further discussion of these issues.

Does this mean that local community studies aren't needed anymore?

Not at all! The data synthesis is not intended to replace the need for local or targeted studies of the Jewish community. Rather, it fills a specific gap that has persisted in survey research of American Jews for more than 40 years. All survey data requires adjustments or weighting to the known population from which it is sampled. Typically this is done using the US Census. However, this has not been possible because census data does not include a question about religion or Jewish identity. Weighting that is done in local surveys typically adjust for standard demographics of the area, with the assumption that the Jews who ended up in the sample are representative of all Jews in the target area. There is no way to evaluate or adjust for whether the Jewish sample is representative of all Jews in the area. Especially where local surveys resort to heavily advertising the survey to increase response rates among the Jewish population, this can lead to an inflation in the estimation of the size of the population. The data synthesis provides Census-like data for the Jewish population in order to provide a population profile that can serve as a baseline for those conducting targeted surveys and studies of the population.

How do I use this map?

As your mouse moves over states, the population for the state is in the hover box that appears over the map. Upon clicking on a state, the map centers to that state and you can view the detailed population estimates, along with demographic and institutional data for the state, in the charts below the map. Once a state is selected, you can view estimates by metropolitan areas and counties by clicking on the Metro Area and County buttons on the top left of the map. Moving the mouse over geographic regions (metropolitan areas or counties) will display population estimates in the hover box. Clicking on a region will lock it in place and display the detailed population estimates along with demographic characteristics in the bottom panel. Use the +/- and navigation buttons on the top left of the map to navigate to other states. To display estimates for another state, zoom out using the reset button reset button to return the map to the full United States view.

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How can we use your data in our study or community?

We would love to speak with you to see how we can help. Get in touch with us using one of the links on the website, or send an email to ajpp@brandeis.edu.

Can you provide custom tables?

Don't see detailed tables you need on our data page? Contact us! We're happy to work with you to provide comparisons you need. Send an email to ajpp@brandeis.edu.