Formative and summative usability studies

The difference between formative and summative studies is determined by the development stage of the interface to be tested and the goal of the test. Formative, or exploratory, studies are run on early versions of the product when it is still being designed with the aim of understanding user behavior, needs, and wants, and how people expect to interact with the product while summative, or assessment, studies are run on half-completed to completed products, with the aim of validating the improvements made as a result of previous formative tests, validating individual features or determining a baseline usability. Formative studies are run to shape the product while summative studies are run to assess its usability. Jeff Sauro describes this as follows:

Both types are compatible with remote methodologies.