Measurement Uncertainty

the bounds that should be placed on a measured value because of uncertainties in themeasurement. If there are several factors pertaining to the measurement, such asvoltage bias and temperature bias and precision of measurement scale,the total measurement uncertainty can be difficult to calculate and may be larger thanthe largest individual uncertainty of any one factor depending on the sensitivity ofthe measurement to the significant factors. There is no such thing as a perfectmeasurement, although some measurements are so precise that errors are negligible.Solar irradiance measurements are notoriously unreliable with the best methods (1% to3% uncertainty, which means that an “excellent” method can produce results that maydiffer as much as 50 W/m2), and can become worthless (10% to 30% uncertainty)with careless methods.