Cultural consensus theory supports a framework for the measurement and evaluation of beliefs as cultural; shared to some extent by a group of individuals. Cultural consensus models guide the aggregation of responses from individuals to estimate (1) the culturally appropriate answers to a series of related questions (when the answers are unknown) and (2) individual competence (cultural competence) in answering those questions. The theory is applicable when there is sufficient agreement across people to assume that a single set of answers exists. The agreement between pairs of individuals is used to estimate individual cultural competence. Answers are estimated by weighting responses of individuals by their competence and then combining responses.
Cultural consensus theory assumes that cultural beliefs are learned and shared across people. Since the amount of information in a culture is too large for any one individual to master, individuals know different subsets of the cultural knowledge and vary in their cultural competence. Cultural beliefs are beliefs held by a majority of culture members. Given a set of questions, on the same topic, shared cultural beliefs or norms regarding the answers can be estimated by aggregating the responses across a sample of culture members. When agreement is close to absolute, estimating answers is straightforward. The problem addressed by cultural consensus theory is how to estimate beliefs when there is some degree of heterogeneity present in responses. In general, cultural consensus theory provides a framework for determining whether responses are sufficiently homogeneous to estimate a single set of shared answers, and then estimating the answers and individual cultural competence in answering the questions.
Cultural consensus models do not create consensus or explain why consensus exists; they simply facilitate the discovery and description of possible consensus. A high degree of agreement among raters must be present in responses in order to use consensus theory – only with high agreement does it make sense to aggregate responses to estimate beliefs of the group. Although there are statistical methods to evaluate whether agreement among raters is greater than chance (Binomial test, Friedman test, or Kendall’s coefficient of concordance), these methods do not provide a best estimate of the “true” answers nor do they estimate competence of the raters. Cultural consensus theory is able to estimate competence from the agreement between subjects and then, answers are estimated by “weighting” individual responses by competence prior to aggregation.