The term ε {\displaystyle \varepsilon } is a random variable representing all other factors that may have direct influence on wage. The econometric goal is to estimate the parameters, β 0 and β 1 {\displaystyle \beta _{0}{\mbox{ and }}\beta _{1}} under specific assumptions about the random variable ε {\displaystyle \varepsilon } . For example, if ε {\displaystyle \varepsilon } is uncorrelated with years of education, then the equation can be estimated with ordinary least squares.