When you transform your data.frame into a
matrix, all values become characters, I don't
think that is what you want... (moreover, you're
trying to compute distance with the "class" names
as one of the variables...)

The best would be to put your "Class" as
row.names and then compute your distances and
`hclust`

:

```
mm<-Median[,-1]
row.names(mm)<-Median[,1]
```

Then you can compute the euclidean distances
between Class with

`dist(mm,method="euclidean")`

:

```
> dist(mm,method="euclidean")
Nigel Paul Kelly
Paul 45.110974
Kelly 8.602325 45.354162
Steve 30.016662 75.033326 31.000000
```

Finally, perform your hierarchical
classification :

```
hac<-hclust(dist(mm,method="euclidean"))
```

and `plot(hac,hang=-1)`

to display
the dendrogram.