The sensitivity of latent trait analysis to choice of prior distribution

Random effects latent trait models involve an arbitrary assumption about the form of the prior distribution of the latent variable(s). Although the form of the analysis does not depend on this assumption, it does affect the estimates of the parameters. It is therefore important to know whether the values of the estimates obtained are sensitive to the choice made. This question is answered mainly by providing numerical evidence that the effect of the prior on the expected one‐ and two‐way marginal proportions is negligible.