<Li> Alternatively, ISO defines accuracy as describing a combination of both types of observational error above (random and systematic), so high accuracy requires both high precision and high trueness . </Li> <P> In simplest terms, given a set of data points from a series of measurements, the set can be said to be precise if the values are close to the average value of the quantity being measured, while the set can be said to be accurate if the values are close to the true value of the quantity being measured . The two concepts are independent of each other, so a particular set of data can be said to be either accurate, or precise, or both, or neither . </P> <P> In the fields of science and engineering, the accuracy of a measurement system is the degree of closeness of measurements of a quantity to that quantity's true value . The precision of a measurement system, related to reproducibility and repeatability, is the degree to which repeated measurements under unchanged conditions show the same results . Although the two words precision and accuracy can be synonymous in colloquial use, they are deliberately contrasted in the context of the scientific method . </P> <P> Interestingly, the field of statistics, where the interpretation of measurements plays a central role, prefers to use the terms bias and variability instead of accuracy and precision: bias is the amount of inaccuracy and variability is the amount of imprecision . </P>

Validity refers to accuracy or correctness of measurement in research