There is a desire for reproducibility. If an experiment is exactly duplicated it will return exactly identical results. Like a calculation of 3 × 5, it does not matter which day, when, or who does the same calculation, the result is reproducibly 15. However, experiments are not exactly reproducible. Sensors age (warm up, corrode, fade) and there are uncontrolled influences on both the experiment (humidity, barometric pressure, human personality, raw material composition) and on its measurement (electromagnetic currents, vibrations, reading parallax, lab analysis, sample aging). Replicate experiments (attempts at exact duplication) will generate a diversity of values, not a single repeated value.