During the past decade new approaches to educational measurement have become more widely recognized and the use of computer programs has been developed to make sound use of the procedures and techniques associated with item response theory. However, the implications of these developments for research methodology have not yet been fully recognized. This Encyclopedia will address not only these changes for which the extent of developments are currently becoming evident but will also look forward to the major advances in the methods employed in empirical research which will arise from the use of improved measurement and scaling procedures.The Encyclopedia is divided into three sections. The first section seeks to provide a broad coverage of topics related to the methods of educational inquiry. The second section includes articles on research methodology and statistical analysis, with consideration given to increasing both the strength of inferences from evidence and the confirmation of hypotheses and models developed from theory The third section contains articles on measurement for educational research and covers the fields of measurement theory, achievement testing, attitude measurement and the applications of measurement in research.