When to use Linear Regression? Explain the equation of a straight line.

When to use

Linear regression is used when the dependent variable shares more or less linear relationship with independent variables. In other words the change in dependent variable is directly proportional to each independent variable, provided other independent variables are kept constant.

Straight line equation

The equation of straight line, i.e. y = mx + c, represents the relationship between 2 variables, where change in y is explained by change in x. If x changes by a certain amount, say a, then change in y would be equal to m * a. The intercept c represents the value of y when x is equal to zero.