The primary reason that the NALS is not valid for the latter purpose is the narrow range and poor alignment of the skills it measures relative to what is being taught and learned in the adult language and literacy educational system. I think teachers should always be concerned about the validity of any assessment, formal or informal. I would also argue that validity is much easier to achieve when assessment is closely aligned with instructional goals and integrated into instructional activities. This is why many assessment specialists see performance-based assessment as a potentially more valid alternative to traditional testing. In terms of construct validity, the advantage of alternative assessment is the opportunity to create more direct and more authentic measures of desired knowledge, skills, and abilities than is typically possible with traditional testing.
Standardized tests are strong on reliability.
Performance based assessments are scored more subjectively and therefore reliability must be strengthened by use of well-structured scoring guidelines and training of teachers to make effective and consistent use of scoring guidelines. A paper and pencil test alone will clearly not suffice to guide this high-stakes decision. On the issue of face validity, performance assessment is again a clear winner. Within an alternative assessment system, learning and assessment activities are combined. A well-structured performance task should also be a learning activity.