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Advances in Online Shopping Interfaces - RePub - Erasmus ...

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14 Map Based Visualization of Product Catalogs<br />

<strong>in</strong> a map ordered as a department store. Both Musicovery 5 and LivePlasma 6 show a map of songs,<br />

where the latter also created a similar map for movies. F<strong>in</strong>ally, YouTube 7 has an option called<br />

Warp!, which recommends movies similar to a movie you watched and shows them <strong>in</strong> a map.<br />

Despite this wide list of commercial map based <strong>in</strong>terfaces, these <strong>in</strong>terfaces lack a, publicly<br />

available, scientific foundation. In this chapter, we discuss several issues <strong>in</strong> product catalog map<br />

<strong>in</strong>terfaces which we have published earlier <strong>in</strong> Kagie, Van Wezel, and Groenen (2007, 2008a,<br />

2008c). This chapter comb<strong>in</strong>es these issues and shows applications on a real e-commerce product<br />

catalog.<br />

In the next section, we first review some scientific methods that can be used to create such<br />

maps that are used <strong>in</strong> the e-commerce doma<strong>in</strong> or <strong>in</strong> related fields. Two of these methods, namely<br />

multidimensional scal<strong>in</strong>g (MDS, see Borg & Groenen, 2005) and nonl<strong>in</strong>ear pr<strong>in</strong>cipal components<br />

analysis (NL-PCA, see Gifi, 1990; L<strong>in</strong>t<strong>in</strong>g, Meulman, Groenen, & Van der Kooij, 2007;<br />

Michailidis & De Leeuw, 1998), are discussed <strong>in</strong> more detail <strong>in</strong> Section 2.3, where they are used<br />

<strong>in</strong> two different approaches to create a product catalog map <strong>in</strong>terface. The first which is based on<br />

MDS uses a flexible dissimilarity measure between products to create the map. This approach<br />

has been published earlier <strong>in</strong> Kagie et al. (2007). The second approach based on NL-PCA and<br />

published earlier <strong>in</strong> Kagie et al. (2008c) has the advantage that it also shows po<strong>in</strong>ts represent<strong>in</strong>g<br />

category values of attributes that can be used for navigation over the map.<br />

One problem <strong>in</strong> both map based visualization and content-based recommendation is that<br />

different characteristics of products are not considered to be equally important by users. In Section<br />

2.4, we <strong>in</strong>troduce a way to determ<strong>in</strong>e attribute weights us<strong>in</strong>g clickstream data. We counted<br />

how often products were sold. Based on the assumption that attributes that have a high <strong>in</strong>fluence<br />

on sales of products are attributes that are considered to be important by users, we estimate a<br />

Poisson regression model (McCullagh & Nelder, 1989; Nelder & Wedderburn, 1972) and derive<br />

weights from that. This approach has earlier been described <strong>in</strong> Kagie et al. (2008a).<br />

All these methods are applied to a new real commercial product catalog of MP3 players<br />

<strong>in</strong> Section 2.5. Prototypes of these methods are available at http://www.brows<strong>in</strong>gmap<br />

.com/mapvis.html. This product catalog was provided by Compare Group, owner of the<br />

Dutch price comparison site http://www.vergelijk.nl. F<strong>in</strong>ally, we will draw conclusions<br />

and give directions for future research <strong>in</strong> Section 2.6.<br />

2.2 Methods for Map Based Visualization<br />

The use of maps display<strong>in</strong>g areas with similar items has become <strong>in</strong>creas<strong>in</strong>gly popular <strong>in</strong> fields<br />

where users need to browse through relatively large collections of data, such as, web search<strong>in</strong>g,<br />

image brows<strong>in</strong>g, and manag<strong>in</strong>g music playlists. Also, map based visualization fits <strong>in</strong> the trend<br />

of visual shopp<strong>in</strong>g <strong>in</strong>terfaces <strong>in</strong>troduced <strong>in</strong> <strong>in</strong>dustry. In this section, we discuss four scientific<br />

methods for map based visualizations <strong>in</strong> the fields mentioned above, where we focus on the<br />

5 http://www.musicovery.com<br />

6 http://www.liveplasma.com<br />

7 http://www.youtube.com

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