Census data are among the most robust of any research data because of the methodology of querying every individual in a country rather than relying upon sampled data. Most researchers could only dream of such methodological rigor and statistical power.
Nonetheless, the vast discrepancy between official LDS membership claims and self-identified religious preferences on national censuses have led some to challenge the reliability of census data. LDS Public Affairs spokesman Dale Bills stated, "There may be any number of reasons for the discrepancy, including personal preferences of some citizens regarding disclosure of their religious affiliation". The data do not bear out such claims. Of the 169,872,856 individuals queried in the 2000 Brazilian census, only 383,953 people, or 0.226%, declined to answer the question on religious affiliation. Fewer than 1% of respondents on the Mexican census (732,630 out of 84,794,454 respondents above age 5) failed to specify a religious preference. Other Latin American censuses demonstrate similarly excellent response rates that any researcher would envy. Furthermore, LDS leaders made strong official requests from the pulpit for local members to declare the LDS faith as their faith of preference in virtually every nation where the census included religious affiliation questions. It is therefore unreasonable to claim that large numbers of believing Latter-day Saints refused to identify their religious preference. Such rationalizations only obscure the obvious reality that the overwhelming majority of those who did not declare the LDS faith to be their faith of preference, in fact, do not consider it to be their faith of preference.
Further corroboration of the accuracy of census data in reporting respondents' religious preferences can be found in the consistent correlation between self-identified religious preferences and official membership for the Jehovah's Witness and Seventh-day Adventist organizations, both of which have member definitions tied to activity. The number of individuals identifying the Jehovah's Witness organization as their faith of preference on Latin American censuses weighs in at between 175% and 206% of official membership figures in these countries, representing both baptized adult members and a large number of affiliates. More individuals identified themselves as Seventh-day Adventists than are officially claimed in each country. The LDS Church enjoys a relatively positive reputation in these nations, and so it is unlikely that Mormons would be less likely than Adventists or Jehovah's Witnesses to express their true religious preferences. The consistently low correlation between LDS membership claims and self-identified census data across many nations, the high correlation between membership and census data for other denominations, and the close correspondence between census data and other research on member self-identification and participation all suggest that census data are reliable.
The comparison between 103,735 self-identified Latter-day Saints reported on the Chilean census and the 57,000 Chileans attending LDS meetings each Sunday suggests that far from short-changing the strength of the Church, census data generously overestimate the quantity of participating, committed international members. This is because national censuses report self-identified religious preferences which do not imply church activity. Without exception, the number of individuals attending church weekly is always less than the number identifying themselves as members of the LDS Church or any other faith on a national census.
The evidence overwhelmingly suggests that census data accurately represent respondents' true religious preferences. Beyond accounting for the exclusion of religious data on young children in some censuses, it is exceedingly difficult to find tenable explanations other than member disengagement for the vast discrepancies between self-identified religious affiliation and church-reported membership claims. Fractional rates of self-identification document that most individuals outside of North America officially claimed on LDS membership rolls do not consider themselves members of the LDS Church, demonstrating that the challenge of inactivity runs far deeper than inadequate socialization, economic hardship, or transportation problems.
 Stack, Peggy Fletcher, "Keeping Members a Challenge for LDS Church," Salt Lake Tribune, July 26, 2005.
 2000 Brazilian Census, Instituto Brasileiro de Geografia e Estatistica, Censo Demográfico 2000, www.ibge.gov.br/english/estatistica/populacao/censo2000.
 Censo general de población y vivienda 2000, Instituto National de Estadística y Geografía, www.inegi.gob.mx.
 2002 Chilean Census, Chilean National Institute of Statistics, www.ine.cl/cd2002/religion.pdf.
 Dr. Ted Lyons, as cited in Stack, Peggy Fletcher, "Building Faith. A Special Report: The LDS Church in Chile," Salt Lake Tribune, March 31, 2006.