Bailey, Michael A. 2001. Ideal Point Estimation with a Small Number of Votes: A Random Effects Approach. Political Analysis 9, 3 (Summer): 192-210.
E-M Algorithm in R / S-Plus for ideal point model with covariates (marginal maximum likelihood item response model)
McCourt School of Public Policy
Old North, Suite 200
37th and O Street, NW
Washington, DC 20057