Accounting for the Uncounted:
Computing Correctives for the 2000 RCMS Data

  Roger Finke and Christopher Scheitle
Pennsylvania State University

This article is reprinted with the generous permission of the Review of Religious Research and the Religious Research Association and was published in the Review of Religious Research, Vol. 47, No.1, (2005).

 The authors would like to thank Clifford Grammich, Dale E. Jones, Richard Houseal, John P. Marcum, Scott Thumma, Wilbur Zelinsky, and the RRR reviewers for helpful comments on earlier drafts of this paper.

The 2000 Religious Congregations and Membership Study (RCMS) provides the most complete enumeration of religious congregations and their members by counties.  Yet, this invaluable data collection suffers from two serious limitations.  First, many denominations and religious groups did not participate in the study, resulting in serious undercounts of the total membership.  Second, the undercounts are closely related to race and ethnicity.  These two limitations distort both the descriptive and inferential statistics calculated from the RCMS data.  This research computes two correctives for the RCMS study.  The first provides a more accurate estimate for the national church adherence rate by counting the uncounted.  The second corrective improves adherence rates for counties, states, and urban areas by adjusting for the racial and ethnic groups undercounted.  After accounting for the uncounted, we estimate that the national adherence rate is 63 percent rather than the 50 percent estimated by using the RCMS data alone.

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The 2000 Religious Congregations and Membership Study (RCMS) is an invaluable resource for religion scholars and practitioners alike.  Providing data on religious congregations and their adherents for 149 denominations in the United States, the RCMS offers the most complete enumeration available by counties, states, and the nation.   The goal of the RCMS is to approximate a census of American religion. 

Yet, the RCMS has two serious limitations.  The most obvious is that not all denominations participated.  Despite the gallant efforts of a highly skilled inter-denominational research team, nearly 11 percent of the adherents reported in the annual Yearbook of American and Canadian Churches (YACC) were not included in the study.   Thus, the first limitation of the RCMS is that it is incomplete.

A second limitation is that the extent of the undercounts varies across regions, distorting regional comparisons and biasing coefficients of bivariate and multivariate statistical analysis.  If the percent of the undercount was consistent across counties and states, the church adherence estimates would be low but comparisons across areas would still be accurate.  In other words, if you lower the church adherence rate of all counties by 20 percent, the relative rank of the counties remains unchanged.  Unfortunately, the degree of the undercount is not uniform.  Instead, the level of the undercount varies dramatically from one area to the next and is closely related to race and ethnicity -- variables frequently included in social science models. 

The first limitation reduces the usefulness of RCMS data for descriptive purposes by underestimating the level of involvement in local congregations.  The second can distort both descriptive and inferential statistics.  Specifically, descriptive accounts of regional variation are inaccurate because the undercounts vary by region and inferential statistics are often biased because the undercounts are closely related to other variables of interest.  Both of these problems mean that the RCMS requires some adjustments before the usefulness of the data can be fully realized.  

This research will attempt to offer these corrections.[1]  First, we will offer a corrective for the national rate of adherence.  For this correction we will focus on the numerator of the rate (i.e. religious adherents) by attempting to offer a more accurate count of religious adherents.  We will draw on a variety of sources to offer a more complete estimate of total adherents in the United States by adding in estimates for groups that did not participate in the RCMS. 

We then provide a more accurate measure of church adherence for counties, states, and urban areas by making adjustments for racial and ethnic groups undercounted in the RCMS.  In this second correction we will be adjusting the denominator for adherence rates.  We will illustrate how the corrected adherence rates offer a more accurate regional profile of American religion and provide less biased measures of religious involvement, especially for research at the county, state, and urban level.  Before computing these correctives, however, we first review how the RCMS was conducted and assess several of the acknowledged weaknesses of the data collection.

Counting the Faithful

After collecting a series of detailed and highly reliable religious censuses from 1850 to 1926, the Bureau of the Census acknowledged that their 1936 report was "seriously incomplete.”  With several groups in the South and West refusing to participate, including many within the Southern Baptists and the Methodist Episcopal Church (South), the 1936 religious census was a bitter disappointment when compared to the earlier censuses.  But if the 1936 census was a disappointment, the 1946 religious census was a complete failure.  Facing stiff resistance from religious groups challenging its propriety, the effort was completely abandoned when Congress denied funding for the latter phases of the project (Christiano, 1987; Finke and Stark, 1992).[2]  Beginning in 1933 the Yearbook of American Churches offered national membership totals by denominations on an annual or biannual basis, but they provided nothing by county, state, or even region.[3]   The result was that no data existed for conducting statistical analyses using counties or states as the unit of analysis, or even for offering descriptive profiles of religion by regions or states.

The National Council of Churches (1956) was the first to offer an alternative to the government-sponsored censuses.  Reporting on churches and church membership data for 109 denominations in 1952, they published Churches and Church Membership in the United States: An Enumeration and Analysis by Counties, States and Regions.  This was followed by a similar study using 1971 membership statistics and was published in 1974 by the Glenmary Research Center (Johnson et al., 1974).  A third study published in 1982 by the Glenmary Research Center used 1979 statistics and had several sponsors including the African Methodist Episcopal Zion Church, the Southern Baptist Convention, the Lutheran Council in the U.S.A., and the National Council of the Churches of Christ (Quinn et al., 1982).  In 1990 the Association of Statisticians of American Religious Bodies (ASARB) sponsored the study, but the results were still published by Glenmary (Bradley et al., 1992). 

The 2000 study of churches and church membership was again sponsored by ASARB, but the title was changed to Religious Congregations and Membership Study (RCMS) to better reflect the diversity of religious groups participating in the study.  Most study materials were housed at the international offices of the Church of the Nazarene, with Richard Houseal and Dale Jones coordinating the data collection.  A large interdenominational team, including Sherri Doty, Clifford Grammich, James E. Horsch, Mac Lynn, John P. Marcum, Kenneth M. Sanchagrin and Richard H. Taylor, was responsible for securing the data from participating denominations.

The study began by inviting every religious group that was identified in the 1999 Yearbook of American and Canadian Churches (YACC) to participate.  This source along with other suggested contacts produced 285 invited groups.  In the end, 149 religious bodies were able to participate in the RCMS.  This may seem like a fairly low response rate, but it includes most of the larger religious bodies in the United States and represented 89.3 percent of all adherents reported in the YACC.

When attempting to provide a standardized measure of church members and adherents, the researchers of the RCMS faced several difficulties.  The first was creating definitions that would make comparisons across groups possible.  Counting objects or people would seem to be an elementary task, however it becomes complicated when it is not entirely clear who is to be counted and how they should be counted.  In the case of counting members of a religious group, who should be considered part of the group?  Are only full members, as defined by the religious group, to be counted?  Are regular participants, even if they are not ‘official members,’ to be counted?  Of course, this begs the question of what defines “regular participation.” 

In the face of these difficulties, the RCMS asked the participants for two numbers.  The first was the number of “individuals with full membership status.”  The criterion for this “membership” number obviously varies from group to group.  The second number asked for was the group’s “total adherents,” defined as “all members, including full members, their children and the estimated number of other participants who are not considered members.”  This latter number was meant to come closer to a standardized number with which to compare groups.

A little less than half (n=67) of the participating groups only provided a full membership number and not a “total adherents” number.  In these cases a total adherents number was estimated by calculating how many children were likely to be part of the religious group.  In other words, the final adherents total included both the adult members reported by the denomination and an estimate of the number of children involved.[4]  The specific formula for estimating adherents from the membership counts is as follows:

Reported Church Members * [Total Population / (Total Population - Children 13 years and under)][5]

By factoring in children 13 years of age and under for denominations not counting children, this total significantly reduces biases when making comparisons across denominations and over time. 

Table 1 shows how the 2000 RCMS compares with previous churches and church membership studies.  Generally the studies have become more inclusive and complete over time.  The percent of YACC adherents included increased from 79.3 percent in 1952 to 94.3 percent in 1990 and then dropped slightly to 89.3 in 2000.   The number of participating religious groups dropped sharply in 1971, from 109 in 1952 to 53 in 1971.  Since 1971, however, the number has steadily increased, reaching 149 in 2000.   Estimates for Jewish groups appeared in the 1952, 1990, and 2000 data.  The 1980 data contained actual counts of 1,501 Conservative and Reform congregations.  However, the 2000 RCMS was the first of the studies to include congregational estimates for Muslims, Baha’is, Buddhists and other groups outside of the Judeo-Christian tradition.  The most serious omission of the studies has been the inability to consistently include accurate counts for most African American churches.

Despite the limitations of the RCMS data, however, the study has several advantages over other attempts to enumerate the religious population of the United States.  As noted earlier, the YACC provides a more complete estimate for congregational membership in the United States, but offers only national estimates and the estimates often rely on different reporting years.  This eliminates the possibility of drawing regional comparisons or conducting more advanced statistical analysis using counties, states, or urban areas as the unit of analysis.  The RCMS also has advantages over large national surveys such as the American Religious Identification Survey (ARIS).  Based on a telephone survey of a large sample of Americans (N= 50,281), the ARIS offers a detailed profile of American religion and allows for statistical analysis using individuals as the unit of analysis, but even this survey cannot offer meaningful membership estimates for counties, states, or urban areas.  Moreover, the survey measures self-reported religious affiliation rather than membership (Kosmin, Mayer and Keysar, 2001).  The 2000 RCMS remains the only recent census of religious membership in America.

Table 1: Comparing the 2000 RCMS to Previous Church and Church Membership Surveys

Notes: *YACC: Yearbook of American and Canadian Churches; NCC: National Council of Churches; AMEZ: African Methodist Episcopal Zion Church; SBC: Southern Baptist Convention;

ASARB: Association of Statisticians of American Religious Bodies; ARDA: American Religion Data Archive (www.TheARDA.com)

A Corrective for the National Adherence Rate

The goal of our correctives is to improve the measure for church adherence.  What percent of the population holds membership in a local religious congregation?  To calculate a total adherence rate for the United States, we must have both a numerator (total number of adherents) and a denominator (total population).  The latter is fairly easy to acquire through Census data, but the former is more difficult to accurately produce.   Our first tactic for improving our measure of church adherence is to make the final count for adherents (the numerator) more complete. 

YACC Omissions

The 2000 RCMS reports a total count of 141,371,963 adherents in the 149 groups participating in the study.   To offer a more complete count, however, we must first identify the religious groups that did not participate in RCMS and then secure an adherent estimate for each group.  We begin with denominations that listed membership totals in the Yearbook of American and Canadian Churches (YACC), but did not participate in RCMS.  Some of these missing groups were unable to provide the desired statistics and others simply refused to participate.  Regardless of the reason, however, the result was an undercount of congregations and church adherents. 

Table 2- 2000 YACC Adherents for Groups Not Participating in the 2000 RCMS  

As shown in Table 2, there were over 29 million adherents reported in the YACC that go uncounted in the RCMS.   The vast majority of these omissions are from 14 denominations with over 100,000 members.  These 14 groups alone account for 27,834,766 additional adherents.  If we add these adherents to the RCMS number, then we get an adherents numerator of 169,206,729.  Returning these adherents to the total corrects for the absence of the historically African American denominations that were not included in the RCMS totals.[6]

There were also an additional 122 groups reported in the YACC with less than 100,000 members that did not participate in the 2000 RCMS.  If we sum the adherents of these smaller groups together this adds another 1,217,725 adherents increasing our numerator to 170,424,454.[7] 

Estimates from Congregational Totals

Additions are also needed for groups that participated in the RCMS, but only provided counts of congregations, not membership or adherents.  Since a few of these groups did list national adherent totals in the YACC, Table 3 displays these groups and reports the adherents numbers provided in the 2000 YACC.  This adds another 376,780 adherents to bring the total to 170,801,234.

Table 3- RCMS Participating Groups Who Did Not Provide Membership-Adherents Numbers and Their 2000 YACC Adherents

There were also a few Christian groups that listed congregational totals, but did not offer membership totals in either the RCMS or the YACC.  These groups, and their congregational totals, are listed in Table 4.  To calculate an adherent estimate for each of these groups, we assumed 150 adherents per congregation.  This assumes that their congregations are less than one half the size of the average Protestant congregation in the 2000 RCMS (322 adherents).   We recognize that many of the groups in Table 4 support small congregations (e.g., Church of Christ, Scientist) that fall far below the national average, but we also know that at least a few of the groups support sizeable congregations.  For example, the Hartford Institute for Religion Research lists 27 of the 728 Calvary Chapel congregations as having a weekly attendance of 2000 or more (Hartford, 2004).  By contrast, only 2 of the 7,314 Episcopal congregations report a weekly attendance of 2000 or more.  In any event, our estimate of 150 adherents per congregation should be a conservative one.  Using this estimate, we add another 1,527,300 adherents to our total.  But this does not include the many small independent\non-denominational congregations not counted by RCMS. 

The RCMS included 1,705 independent\non-denominational congregations, all of which had more than 300 members (see Jones et al., 2002, p. 535).  The Faith Communities Today Project estimated that there are about 35,000 independent congregations in the United States (Dudley and Roozen, 2001) and the Organizing Religious Work study arrived at similar estimates (Ammerman, Lummis, Roozen, and Thumma, 1998).  This means that approximately 33,295 independent congregations were not counted by the RCMS.  Considering that all of these congregations are less than 300 members and some of them will be very small store-front congregations, the mean size of these congregations will be skewed to the lower end of the range.  If we assume that these small congregations have a mean size of 70 members each, then this adds 2,330,650 adherents to our total adherents estimate.  This estimate is supported by data from the National Congregations Study showing that independent congregations with less than 300 regular participants have a mean of 72 ‘regulars’ (Chaves, 1998).[8]  This addition is also noted in Table 4. 

Table 4- Adherents Estimates for Groups Based on Number of Congregations

Notes:  
a.* Number of pastors serving parishes
b. ** Total number of clergy

Non-Christian Additions and Adjustments

One of the many significant new contributions of the 2000 RCMS was the involvement of non-Christian groups in the study.  For Muslims, the RCMS team developed a strategy for estimating total adherents based on data collected by the Faith Communities Today Project (Bagby, Perl, and Froehle, 2001).  These adherent estimates are included in the RCMS totals reported earlier.  For the Hindu, Buddhist, Jain, Sikh, Tao, and Zoroastrian groups, however, only the number of congregations was reported.  This means that our current total is missing the adherents of these non-Christian groups and we must add an estimate to account for them. 

The first step is to find adherent totals for the uncounted Eastern religions.  In an analysis of over twenty-three recent studies and sources, Tom Smith reports that “there is a great consensus that the Hindu population is a little over 1,000,000,” with 74 percent of the estimates falling between one million and 1.5 million adherents (Smith, 2002, p. 581).  We will use the average estimate he finds among all of these sources, which falls at 1,110,000 Hindus. 

On the other hand, Smith found that there is a much larger range of estimates for the Buddhist population, with some sources estimating over 5,000,000 Buddhists and others estimating less than 500,000.  Using data from the GSS and three other sources he calculates that the Buddhist population ranges from 0.5 to 1.0 percent of the total population.  This would equal between 1.4 and 2.8 million adherents to Buddhism.  Because Smith estimates that the total is closer to the lower estimate, we will add a total of 2 million Buddhists to our adherents total.   These two religious groups along with Muslims “account for about half the people following other religions” (ibid. 578). 

According to GSS data from 1991-2000, Smith estimates that the “other Eastern” religions such as Sikhism and Jainism collectively make up about 0.1 percent of the population.  This would equal a population of about 281,422 adherents.  It is unfortunate that this number is rather broad in what it contains, but since we do not have any individual estimates for these “other” groups this will have to do.  Similarly, GSS data shows that Native American religions comprise about 0.1 percent of the population, so we will add another 281,422 adherents to our numerator.  Table 5 shows the adherents estimates for the non-Christian groups.

Table 5-Adherents estimates for non-Christian Groups*

* Estimates for Muslim adherents were included in the RCMS totals and therefore are not included in our corrections. 

Table 5 summarizes our additions for Hindus, Buddhists, and other non-Christian religions.  The table totals to 3,672,844 and, when combined with the previous corrections, brings the RCMS undercount up to 178,332,028.  Before computing a new adherence rate, however, we need to make a final adjustment to the RCMS estimate for Jewish adherents.  The RCMS offers adherents totals for Muslims and Jews, but the count for Jews is based on all Jews (secular and practicing) and requires an adjustment to make it comparable with the other measures of religious adherents.

The RCMS research team acknowledged that their estimate of 6,141,325 Jewish adherents, which comes from the American Jewish Year Book 2001, did not match the RCMS adherent standard used for other denominations (see Jones et al., 2002, p. 535).  Rather than representing the number of people holding membership in a local synagogue or temple, this number represents the total Jewish population.  This is confirmed by other sources.  The 2000 General Social Survey found that self-affiliated Jews made up 2.2 percent of their sample.  If this same percentage was applied to the general population this would translate into 6,191,280 people, or a count very similar to the American Jewish Year Book figure reported by RCMS.  But this figure represents religious affiliation or identity, not membership or participation.  What percent of the Jewish population or those affiliating as Jews should be considered “adherents” in the same way that the other RCMS groups calculated adherents?

To clarify what percentage of the Jewish affiliates held any involvement in the local congregation, we looked at worship service attendance in the GSS 2000 and found that 30.2 percent of all self-identified Jews never attended worship services.  In the absence of any other measure of membership, we use this as an indicator of involvement in the local synagogue or temple.  When we multiply the RCMS adherents estimate for Jews by 30.2 percent we arrive at an estimated 1,854,680 self-identified Jews that would not be considered adherents.   Reducing the RCMS total by this amount results in an adjusted estimate of 4,286,644 Jewish adherents. 

Table 6-Total Adherents Estimates                     

After making all of the corrections and adjustments, we estimate that there are 176,477,348 total adherents representing 62.7 percent of the population.  A national adherence rate that is similar to a previous estimate of 62 percent computed in 1980 (Stark, 1987). 

A Corrective for Counties, States, and Urban Areas

The RCMS survey accounted for 79.1 percent of all religious adherents reported in Table 6.   If the undercounts were evenly distributed across every county in the United States, corrections would be easy.   We could divide the RCMS totals by 79.1 percent of the population and we would have corrected the adherence rate for every county, state, and urban area in the nation.  But the undercounts are not evenly distributed.   As shown earlier in Table 2, the absence of adherent totals for the historically African American denominations is a major omission that shows wide-ranging variation across counties.  To develop a corrective for this omission, we need to adjust the adherence rate to account for the uncounted. 

When developing a corrective for the national adherence rate, attention focused on getting a more complete count.  In other words, we corrected the numerator of the adherence rate because the YACC and other sources provided additional data on the number of church adherents in the nation.  When we offer a corrective for counties and other regional units, however, our attention shifts from the numerator (total adherents) to the denominator (total population).  What is the appropriate denominator when some groups are not fully represented in the numerators count of adherents?  In other words, if only 50 percent of a racial or ethnic group’s adherents are included in the numerator, then only 50 percent of its population should be in denominator. 

The need for this correction is most apparent for African-Americans.  Because none of the large historically African-American denominations are included in the RCMS, we know that there is a severe undercount of black adherents.  This is openly acknowledged by the researchers (Jones et al., 2002, p. xiii).  One solution would be to simply exclude all blacks from the denominator (i.e. total population minus black population), but this solution would ignore the fact that many blacks are members of denominations that are not part of the historically African-American groups.  This means that some blacks are counted among the RCMS groups, so it would not be accurate to exclude all blacks from the population. 

Our second corrective will attempt to find the proportion of church adherents excluded from the 2000 RCMS by race (the numerator) and then exclude an equal proportion of the population from the denominator for each race.  Here our attention will focus on the percent of religious adherents counted for each major racial grouping. For instance, what percent of black adherents are included within the RCMS?  What percent of white adherents?  Calculating the percent of religious adherents uncounted by the RCMS for each race allows us to generate multipliers for adjusting the denominator and greatly improves the estimate for religious adherence. 

The first step in adjusting the denominator is finding the racial breakdown for each denomination.  This allows us to calculate the number of adherents counted and uncounted by race.  For the largest denominations we turned to the American Religious Identification Survey (ARIS) of 2001 and a merged file of the last ten years of the General Social Survey (GSS).  Each survey gave us a large sample of the population with measures for both race and religion.  Whenever possible, and especially for denominations where self-identification was more difficult (e.g., the multiple branches of Baptists), we verified the estimates with denominational reports, denominational surveys, and with brief phone calls or e-mails to those collecting data for the denomination.[9]  For the smaller denominations even the ARIS and the merged GSS files did not have enough cases for racial estimates.  For these denominations we assigned their group the racial breakdown of the larger religious category in which they fell (e.g., Evangelical, Mainline, African-American, Catholic, etc)[10].

Table 7: Number and Percent of Adherents Counted in RCMS by Race