My Papers and Programs

Some of my statistical papers, presentations and computer programs.

Articles and Chapters

Reprints by kind permission of [1] Wolters-Kluwer Publishers, [2] the American Statistical Association, and the [3] the International Biometric Society.


  • Uebersax, J. S. (1994). On the dimensionality of a latent class model. Paper presented at the Annual Meeting of the Classification Society of North America. Summary: principal components or factor analysis of probit-transformed conditional response probabilities lets one:
    • assess the dimensionality of the latent classes;
    • plot latent classes and manifest variables in 1 to K dimensions;
    • approximate a discrete latent trait model model; and
    • interpret and/or diagnose the LCA solution.

Web Articles

These are mostly online articles and do not include my other articles publications.


  • LTA-2 (zipped)
  • Latent Trait Analysis and IRT modeling with dichotomous items or manifest variables. This program will estimate both normal-ogive and logistic-ogive IRT models using the marginal maximum likelihood method. Bayesian (expected a posteriori; EAP) scores are calculated for each respondent or response pattern. The program can be used to estimate a one-factor common factor analysis model for dichotomous items. The program is very user friendly.

  • LLCA (zipped)
  • Located Latent Class Analysis---a discrete latent trait model, with latent classes located on a latent trait dimension, as described in Uebersax JS, JASA, 1993. Includes excecutable program, FORTRAN source, User's Guide, and examples.

  • LTMA (zipped)
  • Latent Trait Mixture Analysis, as described in Uebersax JS, Grove WM, Biometrics, 1993. This model can be understood as a mixture of latent traits, or a form of conditional-dependence LCA. A common use is to estimate accuracy of diagnostic tests in the absence of a "gold standard." Includes excecutable program, FORTRAN source, User's Guide, and examples.

  • glc

    Estimates the latent correlation for pairs of dichotomous variables with a user-specified skewed latent trait distribution; very easy to use.

  • TetMat (zipped)
  • Very user-friendly program to produce a matrix of tetrachoric correlations. Also supplies standard errors, confidence intervals, p-values, and item thresholds. Provisions for smoothing a potentially improper correlation matrix.

  • POLYCORR (web page)
  • POLYCORR 1.1, a program with advanced features to estimate the polychoric correlation coefficient. Calculates the polychoric correlation for a single table, but has many options.

  • tcorr (zipped)
  • Calculate the tetrachoric correlation coefficient. For a single table. Very easy to use--just enter the four frequencies and get the answer. Also reports standard error, item thresholds, etc.

  • MH (web page)
  • Simple program to test marginal homogeneity in 2-way tables using McNemar and Stuart-Maxwell tests. The Bhapkar test is also performed.

  • MVN (web page)
  • An easy-to-use but technically solid program to generate random multivariate-normal data.

  • CONDEP (zipped)
  • Simple program to perform conditional dependence diagnostics on a latent class analysis solution. Includes executable code, QuickBASIC source, instructions, and example.

  • MIXBIN (zipped)
  • User-friendly program to estimate a mixture of binomials. Includes executable program and short documentation.

  • probit (zipped)
  • Simple utility to calculate the probit function.

  • PAIR (zipped)
  • Performs unidimensional scaling based on pair-comparison ratings.

  • CLUSBAS (zipped)
  • Extremely easy to use program for average-linkage hierarchical cluster analysis. Executable code and source code (in both fortran and QuickBasic versions) included. User supplies similiarity/dissimilarity matrix. This version limited to 100 objects, but the limit can be increased. Ideal for cluster analysis of variables/items.

Go to Latent Structure Analysis site
Go to Rater Agreement site

Last updated: 20 Apr 2010 (reprints)

(c) 2000-2010 John Uebersax PhD    email