The least square method is the process of finding the best-fitting curve or line of best fit for
a set of data points by reducing the sum of the squares of the offsets (residual part) of the
points from the curve.
During the process of finding the relation between two variables, the trend of outcomes are
estimated quantitatively. This process is termed as regression analysis.
The method of curve fitting is an approach to regression analysis. This method of fitting
equations which approximates the curves to given raw data is the least squares.
It is quite obvious that the fitting of curves for a particular data set are not always unique. Thus,
it is required to find a curve having a minimal deviation from all the measured data points. This
is known as the best-fitting curve and is found by using the least-squares method.
Also, read:
Correlation and Regression
Linear Regression Formula
R squared Formula in Linear Regression
Least Square Method Definition
The least-squares method is a crucial statistical method that is practised to find a regression line
or a best-fit line for the given pattern. This method is described by an equation with specific
parameters. The method of least squares is generously used in evaluation and regression. In
regression analysis, this method is said to be a standard approach for the approximation of sets of
equations having more equations than the number of unknowns.
The method of least squares actually defines the solution for the minimization of the sum of
squares of deviations or the errors in the result of each equation. Find the formula for sum
of squares of errors, which help to find the variation in observed data.
The least-squares method is often applied in data fitting. The best fit result is assumed to reduce
the sum of squared errors or residuals which are stated to be the differences between the
observed or experimental value and corresponding fitted value given in the model.
There are two basic categories of least-squares problems:
Ordinary or linear least squares
Nonlinear least squares
These depend upon linearity or nonlinearity of the residuals. The linear problems are often seen
in regression analysis in statistics. On the other hand, the non-linear problems are generally used
in the iterative method of refinement in which the model is approximated to the linear one with
each iteration.
, Least Square Method Graph
In linear regression, the line of best fit is a straight line as shown in the following diagram:
The given data points are to be minimized by the method of reducing residuals or offsets of each
point from the line. The vertical offsets are generally used in surface, polynomial and hyperplane
problems, while perpendicular offsets are utilized in common practice.