# Regression Analysis for Curve

Single Regression Analysis
is used when there are one X and one Y.
And it uses the formulation,

It is useful.
But it is the straight line.
This page is made for curves.

##
Use Single Regression Analysis

For example, there is the data,

It looks like a curve.

In this case, we add the variable of square of X

Then we use the new variable as the "X",

We use **X and Y** to make
2-Dimension Scatter Plot
.
But we use **square X and Y** to do regression analysis.

We can use various formulation as X, for example, square X, sin(X), exp(X), log(X) and so on.

##
Use Multi-Regression Analysis

General quadratic curve is

We need the formulation of
Multi-Regression Analysis
.
This is the point that starting data is one X and one Y but analysis data is more than two.

Multi-Regression Analysis is done using the variables, square X and X.

NEXT Prediction Interval of Regression Analysis