Why are age and grade equivalent scores often unreliable?

Age and grade equivalent scores can be unreliable primarily because they do not reflect individual progress adequately. These scores are designed to provide a comparison between a student's performance and that of peers in the same age or grade level. However, they often fail to account for the unique learning trajectories of individual students.

For instance, if a student shows improvement in their abilities but still falls short of the age or grade level expectations due to various factors such as learning disabilities or different learning styles, the age and grade equivalent scores may suggest stagnation or regression, which could misrepresent the student’s actual progress. These scores could also imply that a student is performing at a level significantly lower or higher than they truly are, based on the variability of learning rates among different individuals. This points to the critical need for an assessment approach that takes into account the context of each student's learning development rather than providing a one-size-fits-all comparison through equivalency scores.