In Figure 17.7, we labeled the product points of both a map made by MDS using
equal weights for all attributes and a map made using our weighting approach by
their corresponding Brand. The second map was rotated using Procrustean transformation
[16] to best match the first map. As can be seen in Figure 17.7, the products
having the same brand are more clustered in the second map where brand had been
made more important.
Figure 17.8a shows the second most important attribute, i.e., Memory Size. This
map shows that the MP3 players are generally ordered from cheap at top left to
expensive at the bottom right in the map. The most striking attribute absent in Table
17.3 and, thus, receiving a weight of zero, was Price. However, when we look at
Figure 17.8b where we have made a map labeled by Price, there is a clear pattern in
the map. Both effects exist, since Price highly correlates with other features of MP3
players, such as the Memory Size. These features are, hence, the features explaining
most of the price that is given to a product.
More generally, we can see that the MDS produces a kind of circular shaped map
with some outliers that represent products very different from all other ones. Due to
this, large parts of the map are unused. On the other hand, the map provides at first
sight a good interpretation, where the important attributes show a clear pattern.