Identification based recommender systems make no distinction between users and accounts; all the data collected during account sessions are attributed to a single user. In reality this is not necessarily true for all accounts; several different users who have distinct, and possibly very different, preferences may access the same account. Such accounts are identified as multi-user accounts. Strangely, no serious study considering the existence of multi-user accounts in recommender systems has been undertaken. This report quantifies the affect multi-user accounts have on the predictive capabilities of recommender system, focusing on two popular collaborative filtering algorithms, the kNN user-based and item-based models. The results indicate that while the item-based model is largely resistant to multi-user account corruption the quality of predictions generated by the user-based model is significantly degraded. / text

The term e-Government refers to providing citizens a series of services that can be conveniently conducted over the Internet. However, the potential to redefine and transform e-Government increasingly relies on citizens successfully establishing and managing a user account profile online. E-Government has not adequately addressed user-centric designs for social inclusion of all citizens on e-Government websites. There is a lack of research on the usability of user account management, and a clear lack of innovation in incorporating user-friendly authentication interfaces to accommodate a diverse user population given the wealth of existing research in web authentication techniques within Identity Management. The problem is e-Government has no standardized approach to evaluate and compare the usability of user account interfaces to accommodate a diverse user population and encourage improvements in making user account interfaces more user-friendly and accessible to citizens online. This study proposed extending a well-established usability evaluation methodology called GOMS to evaluate e-Government security interfaces for usability. GOMS, which comprises of Goals, Operations, Methods, and Selection, was used to compare the task time users took to complete similar goals on different websites. GOMS was extended to include Security Cases, which are security related goals users desire to accomplish along with the selected link and trail necessary to satisfy those goals. An observational study was conducted to capture the task time 31 users took to complete similar Security Cases on three popular e-Government websites (DMV.CA.gov, HealthCare.gov, and USPS.com). The study initially defined a catalog of six Security Cases specific to user account management and then established benchmark time predictions for each of the Security Cases using CogTool. The six Security Cases selected were as follows: Registration, Login, Change Settings, Forgot Password, Change Password, and Logout. The task time to complete each of the six Security Case on the three websites, along with statistical analysis and CogTool’s benchmark time predications, were used to quantify and compare the usability of these three websites. In order to capture demographic data and assess participant’s satisfaction using the website, the study conducted a post evaluation survey using the System Usability Scale (SUS). The survey captured age, gender, education, user satisfaction, and computer/security knowledge for each participant to assess design considerations to accommodate a diverse population. Finally, a library of Security Cases was established to compare and highlight the more effective user account interface designs on the three selected e-Government websites. This study found task time data from similar Security Cases could be categorized and used to successfully compare and highlight more effective user account interface designs. The study revealed gender and education had no distinctions in task time when performing user account management related tasks. The study also revealed seniors took significantly longer than any other age group to complete complex user account management interfaces. Additionally, CogTool did not prove to be effective in establishing reliable task time predictions to establish as benchmarks. The study concluded the GOMS method could successfully be used to establish a set of task time metrics in a catalog of Security Cases that can be used to evaluate and compare the usability of user account interfaces to accommodate a diverse user population on e-Government websites. Future usability research should be conducted to evaluate if there is a performance relationship between age and security interface complexity. Future research should also further evaluate GOMS as a viable methodology to evaluate other security interfaces not limited to e-Government and expand upon the library of Security Cases to highlight effective security interfaces designs on other websites to accommodate a diverse user population.

Introduktion: För att kunna använda möjligheterna som internet erbjuder krävs i många fall ett användarkonto som identifierar och autentiserar användaren. En förutsättning för att det ska vara säkert är att ingen annan har tillgång till användarens kontouppgifter, vilket ställer krav på att användaren har komplexa och unika lösenord. Syfte: I denna studie har vi undersökt vilken kunskap användare har kring säkra lösenord, hur de agerar samt undersökt varför de agerar som de gör. Metod: Studien är genomförd som en kvalitativ intervjustudie med 12 respondenter i varierande ålder och bakgrund. Resultat: Våra resultat visar att användarens kunskaper ofta bygger på äldre, ej längre aktuella, rekommendationer. De har även bristande kunskaper om vad en lösenordsgenerator eller lösenordshanterare är och hur de fungerar. Kunskapsbristerna, kombinerat med önskan om att det ska gå snabbt, medför att användarna ej genomför korrekta hot- och konsekvensbedömningar av riskerna på internet. Diskussion/Slutsats: Kunskaperna hos användarna behöver höjas för att minska riskerna de utsätter sig för. Teknikutvecklingen går fort och ökad kunskap och medvetenhet krävs för ett säkert agerande på internet. / Introduction: An account, that identify and authorize the user, is nowadays almost a condition for the user’s ability to use the many services Internet provides. If the account shall remain safe, only the user should have access to the user account. The user needs to create unique and complex passwords. Aim: In this study we have examined the end-user’s knowledge regarding safe passwords, how they act. We have also examined why they act as they do. Method: This qualitative study was made through interviews with 12 respondents of varying age. Results: Our findings show that the user’s knowledge often is based on older recommendations. They also lack knowledge about what a password generator, or a password manger, is and how they work. The lack of knowledge combined with a high wish of swift Internet usage leads to inadequate threat and impact assessments of Internet risks. Conclusion: The end-user’s knowledge, regarding security online needs to be improved, to reduce their risk exposure. The development of technology is moving fast so a raised awareness is mandatory for a safe Internet behavior.