EstimatorIn statistics, an estimator is a rule for calculating an estimate of a given quantity based on observed data: thus the rule (the estimator), the quantity of interest (the estimand) and its result (the estimate) are distinguished. For example, the sample mean is a commonly used estimator of the population mean. There are point and interval estimators. The point estimators yield single-valued results. This is in contrast to an interval estimator, where the result would be a range of plausible values.
Semiparametric modelIn statistics, a semiparametric model is a statistical model that has parametric and nonparametric components. A statistical model is a parameterized family of distributions: indexed by a parameter . A parametric model is a model in which the indexing parameter is a vector in -dimensional Euclidean space, for some nonnegative integer . Thus, is finite-dimensional, and . With a nonparametric model, the set of possible values of the parameter is a subset of some space , which is not necessarily finite-dimensional.
Multivariate t-distributionIn statistics, the multivariate t-distribution (or multivariate Student distribution) is a multivariate probability distribution. It is a generalization to random vectors of the Student's t-distribution, which is a distribution applicable to univariate random variables. While the case of a random matrix could be treated within this structure, the matrix t-distribution is distinct and makes particular use of the matrix structure.
Bessel's correctionIn statistics, Bessel's correction is the use of n − 1 instead of n in the formula for the sample variance and sample standard deviation, where n is the number of observations in a sample. This method corrects the bias in the estimation of the population variance. It also partially corrects the bias in the estimation of the population standard deviation. However, the correction often increases the mean squared error in these estimations. This technique is named after Friedrich Bessel.
ScarcityIn economics, scarcity "refers to the basic fact of life that there exists only a finite amount of human and nonhuman resources which the best technical knowledge is capable of using to produce only limited maximum amounts of each economic good." If the conditions of scarcity didn't exist and an "infinite amount of every good could be produced or human wants fully satisfied ... there would be no economic goods, i.e. goods that are relatively scarce..." Scarcity is the limited availability of a commodity, which may be in demand in the market or by the commons.
Artificial scarcityArtificial scarcity is scarcity of items despite the technology for production or the sufficient capacity for sharing. The most common causes are monopoly pricing structures, such as those enabled by laws that restrict competition or by high fixed costs in a particular marketplace. The inefficiency associated with artificial scarcity is formally known as a deadweight loss. In a capitalist system, an enterprise is judged to be successful and efficient if it is profitable.
