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Weighted least squares (WLS), also known as weighted linear regression, [1] [2] is a generalization of ordinary least squares and linear regression in which knowledge of the unequal variance of observations (heteroscedasticity) is incorporated into the regression.
The method of iteratively reweighted least squares (IRLS) is used to solve certain optimization problems with objective functions of the form of a p-norm: = | |, by an iterative method in which each step involves solving a weighted least squares problem of the form: [1]
Linear least squares (LLS) is the least squares approximation of linear functions to data. It is a set of formulations for solving statistical problems involved in linear regression , including variants for ordinary (unweighted), weighted , and generalized (correlated) residuals .
In ordinary least squares, the definition simplifies to: =, =, where the numerator is the residual sum of squares (RSS). When the fit is just an ordinary mean, then χ ν 2 {\displaystyle \chi _{\nu }^{2}} equals the sample variance , the squared sample standard deviation .
and hence the vector of parameters β can be estimated using least squares. This method of fitting would be inefficient, [ 1 ] and can be improved by adopting an iterative scheme based on weighted least squares , [ 1 ] in which the model from the previous iteration is used to supply estimates of the conditional variances, Var ( Y | X = x ...
The least-squares method was published in 1805 by Legendre and in 1809 by Gauss. The first design of an experiment for polynomial regression appeared in an 1815 paper of Gergonne . [ 3 ] [ 4 ] In the twentieth century, polynomial regression played an important role in the development of regression analysis , with a greater emphasis on issues of ...
Generalized least squares; Generalized estimating equations; Weighted least squares, an alternative formulation; White test — a test for whether heteroskedasticity is present. Newey–West estimator; Quasi-maximum likelihood estimate
Local regression or local polynomial regression, [1] also known as moving regression, [2] is a generalization of the moving average and polynomial regression. [3] Its most common methods, initially developed for scatterplot smoothing, are LOESS (locally estimated scatterplot smoothing) and LOWESS (locally weighted scatterplot smoothing), both pronounced / ˈ l oʊ ɛ s / LOH-ess.