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. This section includes articles that trace the history of educational research and the methods of both humanistic and scientific research which are linked by a key article on research in education: epistemological issues. Other general articles consider the methods of evaluation and policy-oriented research. The contribution of critical theory is also discussed. 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 procedures employed in both the humanistic and scientific approaches, as well as in a wide range of techniques employed in the statistical analysis of both quantitative and qualitative data are also presented. 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. The focus of this section is towards the improvement of measurement for educational research. Articles include updated and revised material from the "International Encyclopedia of Education, 2nd Edition" (described by "Choice" as being "a premier reference work when judged on virtually every criteria applied to a reference work") together with newly commissioned material.