Institute for Objective Measurement - Rasch Scaling information from MESA at the University of Chicago. Includes full text articles. Psychometrics Research Unit - Research results, questionnaires and publications of the Psychometrics Research Unit (University of Valencia, Spain). Content a mixture of English, Spanish, Valencian and Portuguese. Principal Components and Factor Analysis - Chapter from StatSoft's Electronic Statistics Textbook. The Correlation Coefficient - Online textbook by political scientist RJ Rummel. Multivariate Data Analysis - Outline for Michael Friendly's course on multivariate data analysis and linear statistical models in behavioural science research. Includes bibliographies, computing guides, notes, and SAS examples covering topics such as regression, ANOVA, and factor analysis. Understanding Factor Analysis - Online textbook providing overview of factor analysis, by political scientist RJ Rummel. Young, Forrest W. - Emiritus Professor of Quantitative Psychology at the University of North Carolina, Chapel Hill. Includes links to the VISta data visualization software, and plenty of resources for ALSCAL multidimensional scaling, including FORTRAN source code. Psychometrika - Print journal of the Psychometric Society. Subscription and submission information and author instructions. Latent Variable Interactions and Quadratics - Resources focused on latent variable interactions and quadratics. Includes a bibliography, FAQ, Excel templates, full text articles, and full text monograph. Scientific Software International - Statistical software for the social sciences. Includes LISREL for structural equation modeling, HLM for hierarchical data analysis, and BILOG, BILOG-MG, MULTILOG, PARSCALE, and TESTFACT for IRT-based test analysis. Winsteps and Facets Rasch Analysis Software - Software to construct linear measures from ordered qualitative observations. Includes details of training workshops; free student version and manual available for download. PMetric Psychometric Software System - Shareware for designing, applying, developing, and evaluating psychometric scales. The software features a scale editor, reliability analysis, central results database and other features. Paul Barrett - Free software for (advanced) psychometric analyses. Also a number of presentations on psychometrics. The Reliability of Measuring Instruments - Offers Tom Knapp's book on reliability of measurement. Item Response Theory - This website by Lawrence Rudner introduces Item Response Theory, and includes a complete on-line book. L-BFGS-B Nonlinear Optimization Code - Bounded optimisation code (FORTRAN) for numerical analysis, from Northwestern University. Mx - Matrix algebra interpreter and numerical optimizer for structural equation modeling and other types of statistical modeling of data. Includes documentation and example code. Reliability and Validity - Clear introduction to the nature and assessment of test reliability and validity. Psych Press - Developer of online and psychology-based psychometric test materials designed to screen and match individuals to particular roles, industries and companies. Ability Tests and Psychometric Assessments - Provides information, resources, and sample ability tests and personality questionnaires. Includes tips on taking tests and how to prepare for them. Institute of Psychometric Coaching - Offers online practice psychometric tests and courses developed by experienced psychologists. The Psychometrics Forum - Independent group of UK psychometric practitioners. Includes information on the benefits of membership, how to join, news, events and FAQ. Latent Structure Analysis - John Uebersax's resource for researchers interested in latent class analysis and latent class models. Italian Institute of Wartegg - Offers clinical assessment courses, counseling, training and the Wartegg testing methodology. Maydeu-Olivares, Albert - Albert Maydeu-Olivares' homepage at the University of Barcelona: includes some unpublished working papers.