Milica Stojmenovic

Social Network Analysis and Communication in Emergency Response Simulations

In this article, social network analysis (SNA) is applied on two emergency responses, involving chemical, biological, radiological, nuclear, and explosives (CBRNE) simulations. However, SNA has seldom been used in the literature to explain communication breakdowns, leading to the question of “can it?” To examine the applicability of SNA when assessing communication, the SNAs of two CBRNE simulations are compared and the structural differences are related to instances of ineffective communication. Study 1 has two tiers in the response (commanders and first responders) and Study 2 has three tiers, where operations officers are added between the commanders and first responders. A higher percentage of communication breakdowns is found in Study 2, possibly as a result of the additional layer. SNA provides researchers with a convenient representation and summary of team functioning. However, basic SNA does not help researchers distinguish between effective communication and breakdown. Breakdowns are attributed to long multi-hop communications, attributable to larger networks.

Perceived and objective usability and visual appeal in a website domain with a less developed mental model

In Human-Computer Interaction (HCI), the usability and aesthetics of webpages have been studied extensively. However, research into participant experience and expertise with the website domain being studied is often overlooked. This paper strived to acquire an understanding of the relationship between usability and visual appeal by examining it in a domain that had less developed mental models, to exclude the influence of past experiences. Two studies were conducted to (1) find a domain with a less developed mental model and (2) examine correlations between usability and aesthetics in the less familiar domain. Results of Study 1 showed that mental models were weaker for city council websites. Results of Study 2 showed that, for city council websites, pre- and post-use perceived usability and visual appeal, perceived usability and the number of passed tasks, and average number of hovers (objective usability) and visual appeal were all significantly and positively correlated.

Does textual word-of-mouth affect look and feel?

In the field of HCI, website usability and visual appeal have been studied extensively. Participant experience with a website genre influences the use and perception of the website. Word-of-Mouth (WOM), such as user reviews, influences users in hotel, restaurant, movie, and many other e-commerce domains. Thus, a companys or products reputation can alter a consumers behaviour towards that product. Our work aimed to acquire an understanding of the effect of textual WOM on usability and visual appeal. This is a novel approach to the topic. This research was undertaken using an unfamiliar city council website to exclude the influence of ones own past experiences and to allow for greater control of the textual WOM. We found that visual appeal, objective and subjective usability were all influenced by text that established reputations.

How does information diffuse in large recommendation social networks

This article investigates how information diffuses in Douban, an online social network. First, we analyze properties of the user relationships in Douban, observing its degree distribution, network reciprocity, and degree of separation. Second, we propose a method that infers how the information diffuses through this network. Subsequently, using this method we rebuild possible information diffusion graphs, and make statistical observations of the disconnected properties, size distributions, and diffusion patterns in Douban. Based on our empirical analysis, we found that in most cases, information diffuses with multiple origins in Douban. We attribute this to the two different kinds of influence that lead to the diffusion: internal and external influence. Finally, based on the observations, we propose a novel SID model to formulate the diffusions in online social network environments. In the model, there are n iterations. On each iteration, each non-infected node can be infected, either externally with probability Pex, or internally with probability Pin from each of the nodes it follows that were already infected. Our simulation results reveal that the SID model can flexibly portray the diffusion processes in Douban through adjusting these two probabilities.

Benefits and Limitations of the Social Network Analysis When Explaining Instances of Ineffective Communication in Two Chemical, Biological, Radiological, Nuclear, and Explosives Simulations

Social Network Analysis (SNA) was performed on a number of emergency response scenarios, including here on two Chemical, Biological, Radiological, Nuclear, and Explosives (CBRNE) simulations. However, little evidence exists in the literature pertaining to the explanation of communication breakdowns using SNA. In this paper, the SNAs of two CBRNE simulations were compared and the differences in structure were related to instances of ineffective communication. Study 1 had two tiers in the response (commanders and first responders) and Study 2 had three tiers, where Operations (Ops) officers were added between the commanders and first responders. A higher percentage of communication breakdowns were found in Study 2, possibly as a result of the additional layer. However, the two studies had different scenarios and CBRNE responders, both possibly confounding the findings. Researchers using SNA are provided with a convenient representation and summary of team functioning. However basic SNA does not help researchers to distinguish between effective communication and breakdown. Communication breakdowns were attributed to long multi-hop communications, which seldom occurred in the present studies because of the small number of participants in the network, and the large number of communications among them.

Building Website Certificate Mental Models

Expert security users make safer online decisions. However, average users do not have mental models for browser security and web certificates. Thus, they may make unsafe decisions online, putting their sensitive information at risk. Users can learn about browser security and their mental models can be developed using information visualization. We introduce an interactive interface designed for building mental models of web certificates for the average user, through visualization and interaction. This model was implemented to facilitate learning with a Mental Model Builder (MMB). The interface underwent a cognitive walkthrough usability inspection to evaluate the learnability and efficacy of the program. We found that there were unique and useful elements to our visualization of browser certificates. Thus, a 2nd generation interface was created and user-tested. Results show that it was successful in building mental models, and users made safer decisions about trusting websites.

The influence of textual and verbal word-of-mouth on website usability and visual appeal

AbstractWord-of-Mouth (WOM) may impact the perception and experience of website usability and visual appeal. This study aimed to highlight the effects of WOM, implemented textually and verbally, on subjective and objective usability and visual appeal in a web environment. This research was spread over three studies and was undertaken using an unfamiliar city council website to exclude the influence of past experiences and to allow for greater control of WOM implementation. The statistical results showed that both visual appeal and objective and subjective usability were influenced via text that established expectations around these and that the results were only more compelling when verbal WOM was added. The result implications show that when the message is simple, such as it usually is in communication on social media and advertising, then it does impact people’s perceptions of website visual appeal and usability, which may impact future intentions.

Spreading word: author frequency of app user reviews

App stores allow developers to publish new updates directly to users. Users evaluate and leave public reviews of their opinions and experiences for others to see. App ratings and reviews are a purchase determinant for users, and are free user-based usability tests. Existing literature offers approaches to extract information from or to summarise app reviews, but what can we say about the authors themselves? We analysed about 8.7 million iOS app reviews written by over 5.5 million unique authors. We found that 71.5% of authors only wrote one review. Only 13,224 instances of authors re-reviewing were observed, by 12,667 authors for 3,345 apps.

Patterns and modeling of group growth in online social networks

We investigate the group growth in online social networks, by analyzing six different user groups (two million users in total) in Douban Network. The size and longevity of posts in the Douban dataset demonstrate a power-law distribution with exponential cutoff and heavy tail, respectively. The frequency of user interactions follows a two-stage power-law distribution, which can distinguish different types of users. The growth of the number of users and the number of posts/replies generated by the users in a given and same time period, in each group, follow an exponential pattern at the initial stage and oscillate dramatically during the rest of the processes. The number of posts/replies has a power-law relation with the number of active users within a period of time. We propose an empirical growth model, Twisted Growth (TG), to portray the relation between the number of users and the amount of the contents they generated. The model derives equations based on the historical data for deciding coefficients, and the assumtion that the contents in one group will attract new users to join, which will lead to growth of users. Further, the newcomers together with original users will create new contents. We validate our TG model through theoretical analysis and simulations over real datasets.

Emergency Response in Simulated Terrorist Attacks: Usability Lessons Learned

This chapter discusses important and interesting lessons our HCI team have learned from our involvement with the design, development, and evaluation of CBRNE-related projects over the last decade. First, the Medical and Casualty Command Post (MedPost) revealed the importance of providing future users with a plausible scenario allowing them to act out their roles. This provided sufficient information on which to base their part of the user interface. We then address two issues that came to the fore in two further projects. PROBE is a CBRNE management system providing support for police, hazardous materials (hazmat) technicians, and Emergency Medical Services (EMS) teams, and the commercial eXplosives Identification Tool (XIT) aims to transform disparate, often paper-based, information on commercial explosives and articles into a standardized electronic database. Finally, we summarize the “take-away” messages that we believe may be helpful to HCI practitioners facing similar uncertain, often unpredictable, conditions. This chapter discusses important and interesting lessons our HCI team have learned from our involvement with the design, development, and evaluation of CBRNE-related projects over the last decade. First, the Medical and Casualty Command Post (MedPost) revealed the importance of providing future users with a plausible scenario allowing them to act out their roles. This provided sufficient information on which to base their part of the user interface. We then address two issues that came to the fore in two further projects. PROBE is a CBRNE management system providing support for police, hazardous materials (hazmat) technicians, and Emergency Medical Services (EMS) teams, and the commercial eXplosives Identification Tool (XIT) aims to transform disparate, often paper-based, information on commercial explosives and articles into a standardized electronic database. Finally, we summarize the “take-away” messages that we believe may be helpful to HCI practitioners facing similar uncertain, often unpredictable, conditions. Keywords: emergency response, crisis management, CBRNE events, first responders, criminal investigations, explosives materials