ABSTRACT
This chapter focuses on the ideas first presented in Wasserman Rachel H regarding the application and value of G-theory for psychotherapy research. Generalizability theory (G-theory) provides a framework within which multiple sources of measurement error can be simultaneously evaluated thus improving the accuracy of reliability estimates and providing critical information for modification and improvement of coding procedures. In an analogous fashion to classical test theory and the application of ICCs, G-theory further distinguishes between decisions based on the relative standing or ranking of individuals relative interpretations and decisions based on the absolute level of their scores. Facets are considered random when the size of the sample is much smaller than the size of the universe and the sample is considered to be interchangeable with any other sample of the same size drawn from the universe.
