A linear regression line has an equation of the kind: Y= a + bX;

Where:

- X is the explanatory variable,
- Y is the dependent variable,
- b is the slope of the line,
- a is the y-intercept (i.e. the value of y when x=0).

**Add the regression line by choosing the “Layout” tab in the “Chart Tools” menu.** **Then select “Trendline” and choose the “Linear Trendline” option**, and the line will appear as shown above.

- Linear regression models the relationship between a dependent and independent variable(s).
- Also known as ordinary least squares (OLS), a linear regression essentially estimates a line of best fit among all variables in the model.
- Regression analysis can be considered robust if the variables are independent, there is no heteroscedasticity, and the error terms of variables are not correlated.
- Modeling linear regression in Excel is easier with the Data Analysis ToolPak.
- Regression output can be interpreted for both the size and strength of a correlation among one or more variables on the dependent variable.