"It should clear from these brief examples of possible approaches to validation that validation is not a once-and-for-all event but rather a dynamic process in which many different types of evidence are gathered and presented in much the same way as a mosaic is constructed: each piece of ceramic or glass is different, sometimes only slightly, sometimes dramatically, from each other piece, but when they are assembled carefully, indeed artfully, they make a coherent picture which viewers can interpret. The process of validation is much like this, presenting many different types of evidence which when taken together, tell a story about the meaning of performance on our test. It is for this reason that I employ the term validity mosaic to characterize the process, bearing in mind that validation is a mosaic that may never be completed, as more and more evidence is brought to bear in helping us interpret performances on our tests, and as changes occur in the purposes of testing, the abilities to be assessed, the contexts of testing, and generalizations test developers want to make." Dan Douglas, Assessing Languages for Specific Purposes (2000) |