This chapter underscores the implicit messages about argument-based validity expressed in the volume. It highlights characteristics of validation illuminated by how the validation research was designed, carried out, interpreted, and presented by each researcher. The chapters show that argument-based validity applies not only to large-scale or high-stakes testing, but is relevant to a range of contexts where assessments are trusted and is called on at varying stages of test development. Argument-based validity has sufficiently detailed concepts for guiding research about technology-assisted testing methods, and it provides terms for defining different types of constructs. Argument-based validity frames research goals that are well-suited to mixed-methods designs, as illustrated in the chapters of this volume. The chapter ends by clarifying the limits of argument-based validation research by reviewing the facts about validation: Validity is not a yes-no decision about a test; validity is not an objective, deterministically derived result; and validity is not the sole responsibility of the experts. Argument-based validity does not change these facts, but rather provides a detailed and logical means of working within these parameters despite the desire of many test users for tests that have been validated by experts and can be adopted uncritically.

Validity Argument in Language Testing: Case Studies of Validation Research introduces argument-based validation and illustrates how the framework is used to conceptualize, design, implement, and interpret validation research for language tests and assessments. The first section introduces the principal concepts and key terms required to understand argument-based validity in language testing, and it identifies argument-based validation studies in language testing. The second section contains chapters reporting argument-based validity research to investigate score interpretation in six language assessments by conducting research on such issues as the reliability of scores, rating quality, the constructs assessed, and the abilities required in the domain of interest. The third part contains three chapters reporting studies of test score use, including their consequences. By presenting each of these studies with reference to a consistent, but customizable, framework for test interpretation and use, the chapters show the contribution of multiple types of investigations and the use of mixed methods research. The volume demonstrates the importance of argument-based validation of assessments for varying purposes and at different stages of test development, for technology-mediated language assessment, and for clarifying constructs definition. It also notes the limits of argument-based validity.