For example, consider Okun's law, which relates GDP growth to the unemployment rate. This relationship is represented in a linear regression where the change in unemployment rate ( Δ Unemployment {\displaystyle \Delta \ {\text{Unemployment}}} ) is a function of an intercept ( β 0 {\displaystyle \beta _{0}} ), a given value of GDP growth multiplied by a slope coefficient β 1 {\displaystyle \beta _{1}} and an error term, ε {\displaystyle \varepsilon } :