CCP is a national omnibus poll of adult Catholics using methods
consistent with the highest quality and academic publishing standards,
including probability-based sampling, multiple language formats, and
statistical weighting of results using the U.S. Census Bureau's Current
Population Surveys (CPS). The CCP is designed as the preeminent
Catholic poll for the United States. Since 2000, CARA has conducted 20
national surveys of self-identified Catholic adults, including more
than 23,000 respondents. For example, the figure below includes
all of the estimates for the percentage of Catholics attending Mass
once a week or more often in these surveys:
the Catholic population is challenging as it is a very specialized
sub-sample of the overall population. Even at 23 percent of the adult
population, there are typically not enough Catholics interviewed in
standard telepone polls of the overall U.S. population to provide for
reliable results. Also, some 35 percent of the Catholic population
self-identifies as Latino or Hispanic and about 15 percent of
interviews with Catholics are typically with a respondent who prefers
to speak Spanish. Below, are some of the methodological features used
to ensure the CCP is as representative as possible:
- The national random sample includes adult, self-identified Catholics in the United States (50 states and the District of Columbia). The number of respondents varies from year to year but always includes at least 800 Catholics, for a margin of sampling error of no more than ±3.5 percentage points. National surveys are typically of sample sizes of at least 800 to 1,000 where the overall margin of sampling error is less than ±4 percentage points and allows for sub-group analyses where the margins of sampling error are less than ±10 percentage points. For example, with a total sample of 1,000, a sub-group that is half of the interviews, or 500 persons, the resulting margin of sampling error would be ±4.4 percentage points. The minimum number of respondents within a sub-group that can be analyzed is about 100, resulting in a margin of sampling error of ±9.8 percentage points.
- Interviews are conducted in both English and Spanish (other languages are available by request) to ensure the sample is representation of Hispanic/Latino Catholics. It is not possible to survey the Catholic population without using Spanish language interviewing. For a more complete discussion of how critical and challenging it is to reach a representative sample of the Hispanic/Latino population see the recently published scholarly article by CARA researchers: "How Many Hispanics are Catholic? Reviewing the Evidence." by Paul Perl, Jennifer Z. Greely, and Mark M. Gray in the Journal for the Scientific Study of Religion, vol. 45, issue 3: pgs. 419-436.
- The polling period typically runs for approximately two weeks. The questionnaire typically takes an average of 12 to 15 minutes of time for a respondent to complete.
- Results of the CCP are presented with statistical weighting. The weights modify selected demographic characteristics of poll respondents to match CARA's best estimates of the actual characteristics of U.S. adult Catholics. For example, if the poll obtains fewer males than are represented among the national Catholic population, the weights adjust for this by placing more emphasis on responses of men than women. .
- CARA polls are conducted either through random digit dial (RDD) telephone methods or are self-administered by respondents from the probability-based sampled national panel of Knowledge Networks.
Results of client commissioned questions are confidential and owned by the CARA client. CARA will not release these results unless requested by the client. However, the core omnibus questions on the demographics of the Catholic population and questions about Catholic background and commitment are publicly released. These are frequently cited in research and by the media. For example see: "Study Sees Church Rebounding From Scandal" in The New York Times, May 18, 2006. For an example of a CARA research report see "Sacraments Today: Beliefs and Practice among U.S. Catholics."