The limits of the confidence interval of a measured or calculated quantity NOTE: The probability of the confidence limits should be specified, preferably as one standard deviation
A measure of how poorly we understand or can predict something such as a parameter or future behavior; in some cases this is the same as a lack of precision
a situation in which an individual has incomplete information as to what is going to happen in the future Economists sometimes distinguish between risk and uncertainty Risk refers to a situation in which an individual knows the possible outcomes that will occur and the probability of each outcome occurring Uncertainty refers to a situation in which the individual is ignorant of all the possible outcomes, the probability associated with known outcomes, or both Insurance is possible in the presence of risk; it may not be possible under more general uncertainty The reader should be aware that, in many contexts outside technical discussion, the two terms are often used interchangeably (adapted from Evans, 1984)
A statistically defined discrepancy between a measured quantity and the true value of that quantity that cannot be corrected by calculation or calibration
A measure used to quantify the plausible maximum and minimum values for emissions from any source, given the biases inherent in the methods used to calculate a point estimate and known sources of error
Uncertainty is a state of doubt about the future or about what is the right thing to do. a period of political uncertainty. the uncertainties of life on the West Coast
The standard deviation of a sufficiently large number of measurements of the same quantity by the same instrument or method The non-correctable part of the inaccuracy of an instrument, it represents the limit of measurement precision The uncertainty of an instrument is caused by the unpredictable effects upon its performance of such factors as friction, backlash, and electronic noise
A lack of knowledge about certain factors in a study which can reduce the confidence in conclusions drawn from data in that study; it is opposed to variability which is a result of true variation in characteristics of the environment
Decision making in which there is no objective basis for assigning numerical probabilities to the different possible outcomes or in which there is no way to describe the possible outcomes Under the Bayesian school of thought the distinction between risk and "uncertainty" is not useful and in fact may not exist In any practical analysis all uncertain situations are assigned probability distributions, either explicitly or implicitly by the selection of the analysis method, whether or not the true probability distribution known A probability distribution is selected for analysis purposes based on experience, intuitive feelings, knowledge, and the lack of knowledge
A measure of variety Uncertainty is zero when all elements are in the same category Uncertainty increases with both the number of categories and their equiprobability [Principia Cybernetica Web]
The reduction of confidence in a conclusion when more than one estimate is available for a variable or more than one structure is available for a model Statistical uncertainty arises when a variable includes a range of estimates within which the true value is likely to be found Inferential uncertainty arises when there are alternative explanations for a measured difference or when extrapolations are made from an estimate Structural uncertainty arises in a model when all the relationships between the various components are not fully demonstrated
The future may contain novelty that is definitely unknowable, i e some future events that cannot be associated with probability distributions based on knowledge of the past (Faber and Proops, 1993)
Distinguished from risk by the fact that there is no scientific basis upon which to formulate any probabilistic argument Applied to the environmental sphere, it refers to long-term consequences that economic activities may have on the environment or health but that the present state of science does not enable us to foresee
Measurement uncertainty is an estimate to a measurement which characterizes the range of values within which the true value is asserted to lie (ISO/DIS 254-1)
Uncertainty is defined as A potential deficiency in any phase or activity of the modeling process that is due to the lack of knowledge " (AIAA G-077-1998)