Which error exists in all measurements and is due to chance?

• A. Trend
• B. Systematic Error
• C. Random Error
• D. Latent Error

Answer: (C)

In measurements, errors fall into random and systematic types. Random error exists in every measurement and comes from unpredictable, chance fluctuations in the measurement process—tiny, uncontrollable factors that vary from one observation to the next. Because these fluctuations are random, repeating measurements and averaging them helps cancel out their effects, which is why random error is tied to the idea that there is always some level of chance-based variation in results. This inherent presence of unpredictable fluctuations is what makes it the best answer.

Systematic error, by contrast, is a bias that consistently shifts results in one direction due to a flaw in the instrument, method, or observer; it isn’t about chance fluctuations present in every measurement. A trend reflects a gradual drift over time, such as instrument calibration changes, rather than the everyday random scatter. Latent error refers to a hidden fault that isn’t detected until it causes a failure, not the everyday randomness of measurement. In practice, we quantify random error with dispersion measures (like standard deviation) and work to reduce it by replication, calibration, and tighter control of conditions.