\begin{Schunk}
\begin{Sinput}
 newx <- expand.grid(gender = levels(dat$gender), athletic = levels(dat$athletic))
 (newx$pred <- predict(m3, newdata = newx))
\end{Sinput}
\begin{Soutput}
       1        2        3        4 
140.7913 180.4243 124.1009 186.0789 
\end{Soutput}
\begin{Sinput}
 grpmeans <-  aggregate(dat$weight, by = list("gender" = dat$gender, "athletic" =  dat$athletic), FUN = mean)
 grpmeans
\end{Sinput}
\begin{Soutput}
  gender athletic        x
1      F      Yes 140.7913
2      M      Yes 180.4243
3      F       No 124.1009
4      M       No 186.0789
\end{Soutput}
\end{Schunk}
