# Single Regression Analysis

If Y is one and X is one, the
Regression Analysis
is called "single regression analysis"

If X variables are more than two, it is called "
Multi-Regression Analysis
".

##
Formulation

By regression analysis, we can study the number of A and B.
And we can study the relation between Y and X and the

.

Least square is the famous way to get the formulation.

##
How to understand the conclusion

###
Analysis of Slope and Intercept

A is called the slope.
B is caaled the the intercept.

We study the relation between X and Y as the set of A and B.

In the analysis of energy and costs, B means the bottom line.
The way to reduce A and B is the efficient improvement.

###
Correlation Coefficient

We evaluate fitting with correlation coefficient.
Coefficient of determination is square of correlation coefficient.
And coefficient of determination is often expressed with percentage.

##
For the case Y is Probability Data

If Y is the probability data, general regression analysis does not work well.
The regeression line does not show the character of probability data.
The straight is not good.

By the change,
log( y / (1-y))

as the new y and we use it for regression analysis, we may get a good output.

If Y is 0 or 1, for example, we should use 0.0000000001 or 0.99999999999 as the Y.
The change may work well.

If you know the change, it is easier to learn
Logistic Regression Analysis
.

NEXT Regression Analysis for Curve