Bayesian Content Validity Coefficients with Credibility Intervals

Bayesian inference for the six rating coefficients proposed by Aiken (1985) and Aiken (1989) : V (content validity), H (homogeneity), C (congruence), R (repeatability), A (rater agreement) and I (item coherence). All six are expressed as functionals of the population distribution of rating categories, so a single Dirichlet-Multinomial model yields their full posterior by push-forward. This treats each judge as one categorical observation and avoids the pseudo-replication of Beta-Binomial formulations. R is modelled on the c-by-c joint table because it is not a functional of the marginal distribution. Provides classical estimates with the correct parity correction, highest density and equal-tailed credibility intervals, posterior threshold probabilities, prior sensitivity analysis and a friendly step-by-step verbose report.