What is the role of test data versus real data in practice tasks?

• A. Real data is always used for testing
• B. Test data checks logic; real data provides realistic context and relevance
• C. Test data is used to replace real data
• D. Real data is never used in practice tasks

Answer: (B)

Test data is used to probe the logic and behavior of a solution, including edge cases, expected outcomes, and robustness. Real data provides a realistic context, reflecting actual patterns, distributions, and user behavior so you can judge whether the approach works well in practice. Using both together ensures your approach is correct in principle and practical in real-world situations. Relying only on real data for testing isn’t always feasible due to privacy and variability, and test data isn’t meant to replace real data or to imply real data isn’t used at all in practice.