Mobile Web Browsing: Usability Stud. Categories and Subject Descriptors. General Terms, страница 3

Kaikkonen and Roto [16] found that the optimal length of a page depends on the page type: an interactive page has to be much shorter than an information page. In their test, six screens were all too long for an interactive page, but 20 screens fine for a text page. In their usability study, a compact list of items on one page

was clearly preferred by the users and recommend close-knit information should not be split on too many pages. Similarly, the results of Giller et al. study lead to the conclusion that in general a designer should have good reasons to use a pagination mechanism instead of a scrolling one [8]. Now, with many mobiles, the scroll control mechanism is sophisticated, so the size of the document being displayed within a scrollable page does not need to be so constrained [13]. Users quickly learn how to scroll and that scrolling is necessary, so avoiding scrolling is not recommended at the cost of adding fetches [2]. Each page should contain as much relevant information as can fit within its capacity. However, depending upon the bandwidth connection, the larger size pages may take longer to load and for some users longer page cluttered

with lots of information without some clear visualizations of the content on small-screen mobile phones might be difficult to browse through. Therefore, in the study of Giller et al., the sum of data and the user statements gathered during the qualitative interviews show the tendency that users prefer deep structures to broad ones although broad ones lead to faster search performances and the most striking reason is the more concise arrangement of items [8]. The experiment presented by Gaven et al. shows that the most effective hierarchy for use with mobile devices is one with only four to eight items on each level and it is better to order in a hierarchy with more levels than in a hierarchy with more items per level [7].

It is clear that considering recommendations from various usability research studies on navigation model are all very important and should be implemented for designing well-organized sites and it may also help improving the adaptive display methods that can be more effective at directing people to the right place by matching user expectations. However, mobile computing is evolving rapidly and due to variations in mobile devices screen size, its features and other related issues, these differences may lead to different rules, such as when the web site is adapted the preferred and optimal page length will also depend on the pages content [8] and what is recommended today may not fulfill the requirements in future changing environment.

Previous research studies show the most important aspect of mobile web browsing is providing easier navigation. If the navigation is designed properly, even very large applications are easily navigable and perhaps the single most important thing to remember when developing an application's navigation is that the user must never become lost in the application [30]. Above all, on small-screen mobile phones, it is more important that users can freely move along, focusing on their task, without having to worry about the site's structure.

3. EXPERIMENTAL DESIGN

This experimental evaluation was carried out on controlled laboratory environment to allow participants perform the task on mobile device browser and desktop browser simultaneously.

3.1 Equipments

In the desktop environment, Internet explorer 6.0 on 17’’ monitor was used for web browsing. For mobile web browsing Sony Ericsson W550i mobile phone was used. None of the participants have ever used this mobile phone.

With a screen size of 1.8 inches (176x220 pixels) and 262,144 color TFT screen, the W550i Walkman mobile phone allows experiencing colorful graphics and images. It has Joystick as a