Standardized tests are most effective when they objectively measure specific knowledge or skills, providing reliable and comparable data across different populations. They are valuable in educational settings for tracking progress, identifying areas for improvement, and making informed decisions about curriculum and instruction.

However, they are at their worst when they lead to teaching to the test, narrowing the curriculum, or when they fail to account for diverse learning styles and backgrounds. They can also add stress to students and teachers and may not accurately reflect a student's overall ability or potential. The effectiveness of standardized tests greatly depends on their design, implementation, and the context in which they are used.