What is Ordinary least squares?
[[File:Okuns law quarterly differences.svg|300px|thumb|[[Okun's law]] in [[macroeconomics]] states that in an economy the [[GDP]] growth should depend linearly on the changes in the [[unemployment]] rate. Here the '''ordinary least squares''' method is used to construct the regression line describing this law. The observed values are shown in blue, the expected ones are shown in black.]] '''Ordinary least squares''' or '''linear least squares''' is a method for estimating unknown [[Statistical parameter|parameter]]s in [[statistics]]. It is a method used in [[linear regression]]. The goal of the method is to minimize the difference between the observed responses and the responses predicted by the linear approximation of the data. A smaller difference means that model fits the data better. Ordinary least squares is a special case of a method commonly called [[least squares]]. The resulting estimator can be expressed by a simple formula. {{Statistics}} [[Category:Statistics]] [[Category:Mathematical approximation]]