You may also need to download and install .Net Framework 4.0.

IATA is a software package for analysing psychometric and educational assessment data. It performs factor analysis, item response theory (IRT) scaling and calibration, differential item functioning (DIF) analysis, computer aided test development, equating, IRT-based standard setting, score conditioning, and plausible value generation. IATA is provided free by Fernando Cartwright and was developed with a great deal of support from many people, with special thanks to Vincent Greaney and others from the World Bank.