Thomas Grechenig

show-me: water consumption at a glance to promote water conservation in the shower

Water is a scarce resource worldwide. Yet, we have many opportunities to conserve it. One particular opportunity for water conservation is the shower, because depending on the shower head and shower habits, an individual can save many liters of fresh water each day. Feedback proved to be an effective method to promote sustainable behavior. Therefore, in this paper we suggest to promote water conservation by providing feedback in form of an ambient display that can easily be integrated in current shower types. We built a prototype to study the potential of such a feedback device. These shower water meter (show-me) display the amount of water, that is used during one shower in form of LEDs assembled on a stick. Thus, an increasing water level is visualized. The user study revealed two groups. The subjects who considered themselves as ecologically conscious changed their behavior and turned the water down or off while soaping. Also, they are willing to pursue this behavior. Other subjects who did not have the goal to act more sustainable, were surprised about their water consumption and tried to reduce it. However, after the removal of the show-me device they did not maintain their behavior and fell back into their previous habit.

Comparing the immediate usability of graffiti 2 and virtual keyboard

This paper presents the results of an empirical study on the input system of the most frequent PDA operating system, PalmOS from Palm Inc. In an experiment with novice users we compared the stroke based alphabet Graffiti 2 with the Virtual Keyboard and the predictive add-on WordComplete from CIC Software for Graffiti 2. We found that although text input with Graffiti 2 was significantly slower and generated a higher error rate (9 wpm; 19%) than text input with the Virtual Keyboard (13 wpm; 4%), there was no significant difference in usability and task load rating. WordComplete for Graffiti 2 had no significant impact on performance but enhanced user comfort.

Using reading techniques to focus inspection performance

Software inspection is a quality assurance method to detect defects early during the software development process. For inspection planning there are defect detection techniques, so-called reading techniques, which let the inspection planner focus the effectiveness of individual inspectors on specific sets of defects. For realistic planning it is important to use empirically evaluated defect detection techniques. We report on the replication of a large-scale experiment in an academic environment. The experiment evaluated the effectiveness of defect detection for inspectors who use a checklist or focused scenarios on individual and team level. A main finding of the experiments is that the teams were effective to find defects: In both experiments the inspection teams found on average more than 70% of the defects in the product. The checklist consistently was overall somewhat more effective on individual level, while the scenarios traded overall defect detection effectiveness for much better effectiveness regarding their target focus, in our case specific parts of the documents. Another main result of the study is that scenario-based reading techniques can be used in inspection planning to focus individual performance without significant loss of effectiveness on team level.

Evaluating the Effect of Style in Information Visualization

This paper reports on a between-subject, comparative online study of three information visualization demonstrators that each displayed the same dataset by way of an identical scatterplot technique, yet were different in style in terms of visual and interactive embellishment. We validated stylistic adherence and integrity through a separate experiment in which a small cohort of participants assigned our three demonstrators to predefined groups of stylistic examples, after which they described the styles with their own words. From the online study, we discovered significant differences in how participants execute specific interaction operations, and the types of insights that followed from them. However, in spite of significant differences in apparent usability, enjoyability and usefulness between the style demonstrators, no variation was found on the self-reported depth, expert-rated depth, confidence or difficulty of the resulting insights. Three different methods of insight analysis have been applied, revealing how style impacts the creation of insights, ranging from higher-level pattern seeking to a more reflective and interpretative engagement with content, which is what underlies the patterns. As this study only forms the first step in determining how the impact of style in information visualization could be best evaluated, we propose several guidelines and tips on how to gather, compare and categorize insights through an online evaluation study, particularly in terms of analyzing the concise, yet wide variety of insights and observations in a trustworthy and reproducable manner.

TwoStick: writing with a game controller

We report the design and evaluation of a novel game controller text entry method called TwoStick. The design is based on the review of previous work and several rounds of pilot testing. We compared user performance with TwoStick experimentally to a selection keyboard which is the de facto standard of game controller text entry. Eight participants completed 20 fifteen-minute sessions with both text entry methods. In the beginning TwoStick was slower (4.3 wpm, uncorrected error rate = 0.68%) than the selection keyboard (5.6 wpm, 0.85%). During the last session TwoStick was faster (14.9 wpm, 0.86% vs. 12.9 wpm, 0.27%). Qualitative results indicated that TwoStick was more fun and easier to use than the selection keyboard.

GeoPointing: evaluating the performance of orientation-aware location-based interaction under real-world conditions

The growing trend towards mobile phones with integrated GPS clearly suggests that navigation and location-based services (LBS) will be key applications for future mobile devices. New hardware features that are currently finding their way into state-of-the-art phones–such as digital compasses and tilt sensors–promise to drive the adoption of mobile geospatial services, and to change the way people navigate, explore and interact with their physical environment: location-based applications that exploit attitude information to realise orientation-aware interaction have been discussed in research for several years. Yet, few actual results on the achievable real-world performance of such systems exist in literature. In this article, we report on a series of function trials carried out with a prototype Geo-Wand–a portable system that allows users to access geo-referenced information by physically pointing towards objects in the real world. The application was realised with a mass market mobile phone connected to a Bluetooth GPS and a custom-built orientation sensor module. We present test results for multiple types of urban terrain and discuss the possibilities and limitations of this next-generation mobile LBS technology.

Dimensions of software engineering course design

A vast variety of topics relate to the field of Software Engineering. Some universities implement curricula covering all aspects of Software Engineering. A number of other courses cover detailed aspects, e.g. programming, usability and security issues, analysis, architecture, design, and quality. Other universities offer general curricula considering Software Engineering in few or single course only. In each case, a course set has to be defined which directly relates to a specific student outcome. This work provides a method for categorizing and analyzing a course set within abstract dimensions for course design. We subsequently show the results of applying the dimensions to the course degree scheme in use. The course design dimensions can also be related to the student outcomes defined in SE2004 CC Section 3.2 [10].

Accessible real-world tagging through audio-tactile location markers

Real-world tagging technologies, such as RFID or visual codes, have enabled new application scenarios that foster mobile interaction with the physical world. While the application scenarios are promising for many contexts, the technologies are currently lacking accessibility. Especially blind and visually impaired people are not able to interact with tags if they are not aware of their presence. We propose audio-tactile location markers as a remedy to this problem. An audible signal leads users to the tag, which can be identified through tactile exploration. Preliminary user studies with four blindfolded subjects using an initial prototype showed the applicability of using an audible signal for locating tags.

Personal and private calendar interfaces support private patterns: diaries, relations, emotional expressions

This paper yields new insights into the emotional value of personal calendars for their users and explores their habits. Using an ethnographic approach we collected data about personal scheduling and revealed highly interesting aspects that are particular valid for private calendars. Interestingly, we found that users still prefer paper calendars although they have access to PDAs and desktop interfaces. One of the main reasons for this is that the calendar represents an integrated all-in-one tool, and the properties of paper support this functionality more efficient than rigid digital calendars. We further observed that calendars have an important emotional value to their users, recording states of relations and emotional expressions like diaries. Based on our results we raise broad issues for the design of calendars that exploit the potential of advanced technology.

Comparing viewing and filtering techniques for mobile urban exploration

The exploration of the immediate surroundings through mobile location-aware devices is starting to become an everyday urban activity. Due to the increasing amount of available geo-referenced information, advanced viewing and filtering techniques need to be investigated as a complementation to simple present-day 2D-map presentations. This article examines both well-established techniques (2D map, list view, category view) and advanced concepts (3D map, tag cloud) regarding their support of mobile urban exploration. In a field study, 26 participants used an experimental multi-view prototype for viewing and filtering tasks on a route through an urban environment. The results show that content-based views may provide similarly good support for viewing the content as spatial interfaces. Furthermore, the experiment provides evidence that the advantages of content-based filtering techniques are increasingly preferred to spatial ones in regard to the amount of available information.