\begin{Schunk}
\begin{Sinput}
     attributes(dat$ed)
\end{Sinput}
\begin{Soutput}
NULL
\end{Soutput}
\begin{Sinput}
     is.numeric(dat$ed)
\end{Sinput}
\begin{Soutput}
[1] TRUE
\end{Soutput}
\begin{Sinput}
     is.factor(dat$ed)
\end{Sinput}
\begin{Soutput}
[1] FALSE
\end{Soutput}
\end{Schunk}
