\begin{Schunk}
\begin{Sinput}
 anova( mod4, mod2,  test="F")
\end{Sinput}
\begin{Soutput}
Analysis of Variance Table

Model 1: wage ~ occupationf2
Model 2: wage ~ occupationf
  Res.Df   RSS Df Sum of Sq      F Pr(>F)
1    531 11605                           
2    528 11539  3     66.19 1.0096 0.3881
\end{Soutput}
\end{Schunk}
