Diagnostic tests are designed to locate specific learning deficiencies in individuals to help identify what concepts a learner has grasped and what areas need improvement. The tests analyze learning strengths and weaknesses at different stages. Correct answers indicate strengths while incorrect responses point to weaknesses. Diagnostic tests can also reveal issues with teaching methods if many students struggle with the same content. They are analytical, qualitative tests that systematically cover all learning points to form the basis for remedial instruction tailored to individual students.