Intelligent Navigation for Mobile Internet Portals - Semantic Scholar

Intelligent Navigation for Mobile Internet Portals Barry Smyth & Paul Cotter ChangingWorlds Ltd. Trintech Building South County Business Park Leopardstown, Dublin 18, Ireland {firstname.lastname}@changingworlds.com Abstract Paradoxically, the mobile Internet represents both a dramatic step forward and a significant step backward from an information access standpoint. While it offers users greater access to valuable information and services “on the move”, mobile handsets are hardly the ideal access device in terms of their screen-size and input capabilities. As a result mobile Internet users are often frustrated by how difficult it is in practice to quickly access the right information at the right time. In our research we have focused on how artificial intelligence techniques can provide practical solutions to these access problems. In this paper we describe an approach to intelligent navigation that has been proven to reduce content access times by 50% in mobile portals thereby enhancing the user experience and leading directly to significant increases in usage.

1

Introduction

The promise of the mobile Internet (MI) is a compelling one: instant access to relevant information and a range of online services (from email and news to games and maps) all from your mobile phone or personal digital assistant (PDA). Unfortunately, the mobile Internet has largely failed to live up to the marketing hype and the resulting inflated user expectations. The reasons for this are many and varied but a key problem relates to usability [Anderson et al., 2001; Buchanan et al., 2001; Miyamoto et al., 2002; Ramsey and Nielsen, 2000; Smyth and Cotter, 2002b; 2002a; Smyth, 2002] and in this paper we consider key factors that impact the usability of mobile portals, which are the primary source of information access on today’s mobile Internet-enabled devices. In particular, we argue that the way in which mobile portals are designed is fundamentally flawed given the capabilities of MI devices and the expectations of MI users (see also [Miyamoto et al., 2002] for a related viewpoint). To a large extent, the design of a mobile portal mirrors the design of a more traditional Web portal: a large collection of content services organised within a category hierarchy of menus and options (see Figure 1 for an example of part of a mobile portal). To access a particular content service the mobile user must navigate through this system of menus in order

Figure 1: Part of a sample mobile portal showing 3 levels of options. The insert shows an example of how one menu level might be presented using a modern handset.

to locate the target content. This is not so much of a problem on the traditional Internet; after all many options can be easily presented on the large screen of a typical PC, and it is relatively easy for a user to access these options through a keyboard or mouse. However, ease of navigation is not a feature of the MI. Content on mobile portals can be more that 15 or 20 clicks away from the portal home page, and this means that MI users can spend a significant amount of their time online simply navigating to content. In this paper we describe how the usability of mobile portals can be significantly enhanced by the use of so-called intelligent navigation techniques. These techniques combine ideas from artificial intelligence, user profiling and information filtering in order to automatically adapt the structure of a portal to the precise needs of an individual user. In short, the navigation structure of the portal is fine-tuned with respect to a user’s access patterns so that relevant menus and services are intelligently promoted to the right user at the right time. Furthermore we present summary results from a comprehensive evaluation of these techniques and show how intelligent navigation can radically improve the efficiency of mobile information access leading to dramatic increases in MI usage. The techniques described herein are fully implemented within the ClixSmart NavigatorT M product by ChangingWorlds (www.changingworlds.com) and are now deployed by Europe’s leading mobile operators including Vodafone and O2 .

2

The Mobile Internet

The mobile Internet refers to the delivery of data services across wireless networks for Internet-enabled handsets as implemented through a group of related infrastructure, protocol and device technologies. The MI allows the end-user to access various types of data services from their mobile handsets, including Web-style information content, email services, games, maps etc. Access devices range from limited, firstgeneration WAP (Wireless Application Protocol) phones to today’s sophisticated PDAs and so-called smart phones. In the past the usability of mobile services has been compromised by limited device functionality, bandwidth, and content. Fortunately the new generation of mobile services (so-called 2.5G services) represents a significant improvement so that major bandwidth and content issues have largely been resolved, with the latest phones offering users significant interface and functionality improvements over the original models. However key usability problems remain due to poor mobile portal design. The core problem is that the menu-driven nature of mobile portals, whereby users access content services by navigating through a series of hierarchical menus, means that users are spending a significant amount of their time on-line navigating to content (their navigation time) and relatively limited time interacting with content (their content time). This limits the overall user experience since navigation time is essentially valueless; time spent navigating to content is considered a waste of time from the user’s perspective [Ramsey and Nielsen, 2000; Smyth, 2002].

2.1 Mobile Internet Devices From a user experience viewpoint, one of the key features of the mobile Internet is the degree to which existing consumer devices represent a significant step backwards in terms of their functionality, at least when compared to the traditional Internet device (the desktop PC or laptop). In particular, presentation and input capabilities tend to be extremely limited on most mobile devices. For instance, a typical desktop PC, with a screen size of 1024x768 pixels, offers mode than 10 times the screen real-estate of a PDA, and more than 20 times the screen space of second-generation Internet phones (eg. I-mode and Vodafone Live! handsets or Microsoft’s SmartPhone). Mobile handsets are further limited by their capacity to receive user input. The keyboard and mouse functionality of a modern PC are notably absent and the mobile phone numeric keypad makes it extremely difficult for user to input any quantity of information. From a mobile Internet viewpoint, these devices restrict input features to simple scroll and select keys that allow the user to scroll through menu lists and perform simple selections. Some improvements are present in most PDAs, which tend to offer touch sensitive screens that are easier to manipulate. Nevertheless data input remains difficult at best.

2.2 Mobile Information Access These key differences that exist between mobile handsets and more traditional Internet devices, such as PCs and laptops, directly influence the manner in which users access information using these devices. For example, on the Internet today search has largely become the primary mode of information access. It is relatively easy for users to input search queries and search engines have improved significantly in their ability to respond intelligently to user needs. In addition the large screen sizes make it feasible for users to efficiently parse the longs lists of search results returned. In contrast, search is far more problematic on mobile devices (see Fig. 2). Entering queries is simply too time consuming and complex for the average user to tolerate and small screen sizes make it practically impossible for users to easily process the result lists returned. As a result, browsing is the primary mode of information access on the mobile Internet. Instead of searching for information, users attempt to navigate to information by using mobile portals. Today the vast majority of mobile Internet services are accessed via an operator portal with direct search constituting a small fraction ( 40%) end before the users locate content. Indeed in the user session results we see that the average number of session per user during the control period is less than 1 (0.9) indicating that some users do not enjoy successful sessions on the days that they access the portal; this must surely damage the perceived value of the portal for these users. In fact we have found that intelligent navigation increases the number of successful sessions by converting failed sessions into successful ones. In other words, overall the trialists in this study tended to engage in the same number of sessions per day during the control and personalization periods, but the percentage of failed sessions fell by 50% from the control to the personalization period. In other words, by helping users to navigate to content more effectively, intelligent navigation is capable of eliminating many of the failed sessions that were previous due to navigation difficulties.

4.4 Site Hits So far we have seen how users are engaging in additional content time and sessions as a result of personalization. How are they spending this extra time? For example, are they going to additional content sites or are they simply spending extra time in their usual favourites? The so-called content discovery problem refers to the challenge of how best to help users to discover new content services on a portal and how to encourage them to visit these services. It is especially important to mobile operators in order to maximise the return on investment for new content services.

Figure 10: Site hit results. Fig. 10 shows that the average number of site hits (individual accesses to content sites) increases by nearly 25% when we compare the 4-week personalization period to the static period. In other words, users are spending their extra time online going to extra content sites - the new found ease with which users can access content leads them to additional sites. And thus there is clear evidence to indicate that personalizing the navigation structure of a mobile portal aids content discovery.

5

Conclusions

In general, limited usability and poor value-for-money are major contributing factors to the low levels of interest in the mobile Internet currently shown by the general public. These problems are closely aligned with the difficulty that users have in locating content on mobile portals, and they are easily frustrated by the amount of time that they are expected to devote to navigating to content through multiple layers of menus and icons. This navigation problem is far more acute on the mobile Internet than on the traditional Internet for a variety of reasons. By their very nature, mobile devices are limited by their small screens and restricted input capabilities, making it particularly cumbersome for users to manipulate the hierarchical menu structures that are used to organise content in a mobile portal. In addition, since mobile portals are organised according to a one size fits all policy many compromises are made with respect to the placement of content services, and so exacerbates the navigation problem for many individual users; for example, popular items for a particular user may well be located far from the portal home page. In this research we have attempted to solve the above challenge by taking advantage of user profiling and personalization techniques in order to automatically adapt the structure of a mobile portal for an individual user, based on their usage history. We have presented the click-distance metric as a model of navigation effort in mobile portals and described a probabilistic personalization technique for restructuring a mobile portal by reordering and promoting menu options in a way that minimises click-distance for a given user. In turn, we have found that this strategy can reduce the average clickdistance for a typical user by 50% in live-user trials.

Of course to be successful it is not sufficient to simply reduce click-distance. The real issue is whether users perceive a usability benefit from this reduction. The evidence from extensive trials suggests that they do, and our studies indicate that significant benefits are available across a range of critical usage metrics (eg. airtime, sessions, page impressions, and site hits). Indeed for every one second of navigation time that is saved users engage in an additional 3 seconds of content time. Similar results to those reported here have been repeatedly found for much larger trials and deployments (in excess of 500k users over an 18 month period) with leading European operators. ClixSmart Navigator is today deployed by Europe’s leading mobile operators including Vodafone and O2 .

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