The characteristic of a written test that measures small differences in achievement between learners is its...

The characteristic of a written test that measures small differences in achievement between learners is defined as discrimination. Discrimination in this context refers to the ability of a test to differentiate between the performances of different learners. A test that has good discriminative qualities will effectively identify not just the overall level of achievement, but also subtle variations in performance among learners. This is particularly important in educational assessments where the goal is to identify specific strengths and weaknesses, and to provide feedback that can guide further learning.

In contrast, validity pertains to whether a test measures what it is intended to measure, while reliability refers to the consistency of the test results over time. Comprehensiveness indicates the extent to which the test covers the relevant content or skills. While all these aspects are important for an effective assessment, it is discrimination that is specifically focused on distinguishing between various levels of achievement.