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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Designing Visual Systems for Social Data Analysis in Open Government Applications</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Jasminko Novak</string-name>
          <email>j.novak@eipcm.org</email>
          <xref ref-type="aff" rid="aff0">0</xref>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Sebastian Preuße</string-name>
          <email>sebastian.preusse@silab.humboldt-viadrina.org</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>European Institute for Participatory Media</institution>
          ,
          <addr-line>Wilhelmstr. 67 10117 Berlin</addr-line>
          ,
          <country country="DE">Germany</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Humboldt-Viadrina School of Governance, Social Innovation Lab</institution>
          ,
          <addr-line>Wilhelmstr. 67 10117 Berlin</addr-line>
          ,
          <country country="DE">Germany</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>University of Applied Sciences Stralsund</institution>
          ,
          <addr-line>Zur Schwedenschanze 15 18435 Stralsund</addr-line>
          ,
          <country country="DE">Germany</country>
        </aff>
      </contrib-group>
      <fpage>7</fpage>
      <lpage>18</lpage>
      <abstract>
        <p>In this paper we discuss our preliminary experiences in designing a visual system for social data analysis in collaboration between citizens and municipal authorities through a web-based open government system. Based on the integration of theoretical models with findings from formative evaluations and stakeholder workshops with a prototype system, we present a multiperspective visualization model and user interface designs addressing specific requirements of social data analysis in heterogeneous stakeholder settings.</p>
      </abstract>
      <kwd-group>
        <kwd>Social Data Analysis</kwd>
        <kwd>Information Visualization</kwd>
        <kwd>Multi-Perspective Visualization</kwd>
        <kwd>Collaborative Sensemaking</kwd>
        <kwd>Open Data</kwd>
        <kwd>Open Government</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>
        The use of information visualization for facilitating the discovery of insights in large
or complex data collections has been extensively researched. Common approaches
consider the use of visualization techniques for augmenting cognitive capabilities of
individual users in recognizing contexts, patterns or relationships in a data collection
as a means of constructing new knowledge [
        <xref ref-type="bibr" rid="ref2">2</xref>
        ]. More recently, there has been a
growing interest in supporting the interpretation of large or complex information sets
through collaborative use of shared visualizations in asynchronous distributed
scenarios. Systems such as Many Eyes [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ] or SenseUs [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ] provide web-based
platforms allowing users to create interactive visualizations of own or shared data
collections and to share them with others. Besides creating customized visualizations
from predefined templates (e.g. pie charts, stacked graphs) such systems allow the
saving and recall of specific visualization states (e.g. zoom, filter or time scale
parameters) which can then be accessed by others (application state bookmarking
[10]). Collaborative analysis is supported by textual comments and graphical
annotations that link user contributions to the related views and vice-versa
(doublelined discussions [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ]). Most recent solutions allow existing visualization systems to be
extended with user comments and discussions [11].
      </p>
      <p>
        The basic idea of such „social data analysis“ [10] is that by coupling visualization
with asynchronous social interaction, the process of individual sensemaking in which
people create new knowledge by collecting, organizing and interpreting information
[
        <xref ref-type="bibr" rid="ref6">6</xref>
        ] can be made more effective [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ]. The associated notion of collaborative
sensemaking emphasises that sensemaking is often a social process in which the
meaning of data and information is negotiated against specific social contexts
involving shared backgrounds, frames of reference, goals and perspectives [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ],[
        <xref ref-type="bibr" rid="ref5">5</xref>
        ].
While these questions may not play a critical role in the above examples of
generalpurpose platforms, they become of central importance when designing for purposeful
collaboration with shared goals, such as in collaborative decision-making in
organizations [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ] or in heterogeneous stakeholder networks with conflicting
perspectives on the meaning of information [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ].
      </p>
      <p>
        Previous research suggests that such contexts require considering specific
requirements in order to support effective sensemaking through exploratory
information access and analysis [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ]. In particular, this refers to the need and potential
of providing visual views of heterogeneous information collections from clearly
defined multiple perspectives reflecting personal points of view of individual users or
shared perspectives of specific user groups. This raises both questions of how such
personal and shared perspectives can be defined as well as how they can be
effectively visualised and made useful for social discovery transfer in heterogeneous
data collections [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ]. Aforementioned approaches do not consider these requirements
and offer only incidental support corresponding to this need (e.g. the possibility of
bookmarking and sharing specific views of the same visualization [10][11]
      </p>
      <p>In this paper we discuss our preliminary experiences in designing a visual system
for social data analysis in collaboration between citizens and municipal authorities
through a web-based open government system. In particular, we discuss the
requirements and design principles for designing visual systems for this specific class
of applications and present one possible solution for turning them into practice. This
is based on the integration of theoretical underpinnings with findings from formative
evaluations and stakeholder workshops with a prototype system. The developed
solution presents a multi-perspective visualization model and user interface designs
incorporating well-known visualization techniques (tree maps, geo-visualisation)
applied in a novel way to satisfy the requirements of social data analysis in
heterogeneous stakeholder settings. In this way, the paper provides an
applicationoriented contribution to this emerging area of research.</p>
    </sec>
    <sec id="sec-2">
      <title>2 Application Setting: Social Data Analysis for Open Government</title>
      <p>
        The underlying idea of open government approaches is that through open publishing
and public analysis of data collections concerning public services better government
and satisfaction of citizen needs can be achieved. Different web portals make various
forms of data collections related to citizen life (e.g. city budgets, transportation
statistics) available online. While such open data collections are being provided by an
increasing number of local and national authorities or citizen initiatives (e.g.
Germany’s Open Data Network), the provision of systems and tools for easy
collection, organization and analysis of this data is still at its beginnings. The few
existing visual tools in this domain typically provide straightforward applications of
well-known visualization techniques (e.g. tree maps of country budgets [
        <xref ref-type="bibr" rid="ref13">15</xref>
        ]) without
considering specific use cases or application settings and their requirements. The
more sophisticated current visual systems for social data analysis (such as [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ], [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ] or
[11]) are designed as general-purpose tools and could in principle be applied to such
contexts, but this has not yet been the case (to the best of our knowledge). Similarly,
none of these approaches consider the existing body of knowledge on supporting
collaboration in heterogeneous settings or the use of visual information interfaces in
such settings [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ].
      </p>
      <p>
        We argue that the effective application of such approaches to the application
domain of open government requires considering specific aspects and requirements of
this particular application context and developing domain-specific solutions. On one
hand, this concerns the inherently problematic nature of the underlying collaborative
scenario. Use cases of social data analysis specifically discussed in previous work
point either to relatively homogeneous user groups with implicit shared interests (e.g.
a group of analysts analyzing a shared data set in [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ]), or encompass a heterogeneous
population of general users sharing and commenting on personal visualizations [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ], or
they refer to a general audience who may become aware of a shared interest defined
by using the visualization (e.g. baby names or job statistics [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ]).
      </p>
      <p>
        In contrast, the open government applications are characterized by a collaboration
setting formed around specific goals and conflicting interests of different user groups
(e.g. citizens, local authorities). Previous research has shown that using visual
information tools to support such contexts requires considering very specific
requirements. This includes the need for providing visual overviews of information
collections from clearly defined perspectives reflecting personal points of view of
individual users or shared perspectives of specific groups of users [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ]. This raises both
questions of how such personal and shared perspectives can be effectively elicited,
visualised and made useful for social discovery transfer in open data collections [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ].
Such concerns are also grounded in theoretical frameworks of collaboration in
heterogeneous settings. The notion of “boundary objects” emphasises the importance
of artefacts which allow perspectives of different user groups to be used
independently while at the same put in relation to each other [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ][
        <xref ref-type="bibr" rid="ref7">7</xref>
        ]. Similar
requirements form the basis of the well-known “perspective making – perspective
taking” model of knowledge transfer [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]. Finally, a number of current practical
initiatives aiming at supporting citizen participation in local government through
easy-to-use tools for collaborative elicitation of citizen needs [
        <xref ref-type="bibr" rid="ref11">13</xref>
        ][
        <xref ref-type="bibr" rid="ref12">14</xref>
        ][
        <xref ref-type="bibr" rid="ref14">16</xref>
        ], reflect an
existing practical need for capturing a shared perspective of a specific stakeholder
group (citizens) and communicating and visualizing it for others (municipal officials).
      </p>
      <p>This raises the following questions: How can we effectively design visual tools for
social data analysis in such heterogeneous application contexts? Which design
principles from literature on collaboration support and from recent general-purpose
visualization platforms can be successfully transferred? What specific requirements
characterize this application context? And can we identify conceptual and design
elements of a specific visualization model that could satisfy such classes of
applications and thus further current practice in this emerging field?</p>
    </sec>
    <sec id="sec-3">
      <title>3 E-Local: A Web Platform for Participatory City Management</title>
      <p>
        We have been investigating these questions within the E-Local project for
participatory city management [
        <xref ref-type="bibr" rid="ref10">12</xref>
        ]. The E-Local project develops a Web2.0 platform
for stimulating active citizen participation in local government through collaborative
elicitation of citizen needs, their interactive visualization and online dialogue between
the citizens and the local administration. A central element of its design is the
datacentric interaction around a shared visualization facilitating online discussion.
      </p>
      <sec id="sec-3-1">
        <title>3.1 Use Case Scenario</title>
        <p>The basic use case of the E-Local project is depicted in Fig. 1. Citizens enter need
requests (e.g. “Please fix the road holes in Wins street”) through the E-Local web
interface or a mobile app. The requests are stored in the E-Local database and
displayed in a geographic visualization based on Google Maps (GPS-data is captured
by the phone app or the user can pinpoint the location). Once the request enters the
ELocal system it can be edited online and forwarded to one’s social network to collect
supporters (via Email, the E-Local network or one’s Facebook account). During this
“mobilization phase” the request can be discussed and commented upon by all users.
After a determined time this phase ends and the request (with corresponding supporter
votes and comments) is forwarded to the municipal administration. This starts the
online dialogue (“feedback and discussion phase”) in which municipal officials can
accept the request and propose a solution or refute it (with an explanation).</p>
        <p>
          In both cases the citizens can vote for accepting or refuting the administration’s
decision. In case of refutal, they can start a citizen initiative for solving the request
and raising the required funding on their own1. All requests accepted by the local
authorities enter the “implementation phase” in which their progress is monitored and
communicated by the local administration. In this way, a model for pro-active citizen
participation in the management of local municipal affairs in a collaborative process
with local authorities is realized (which distinguishes E-Local from other citizen
platforms, such as [
          <xref ref-type="bibr" rid="ref11">13</xref>
          ], [
          <xref ref-type="bibr" rid="ref12">14</xref>
          ], [
          <xref ref-type="bibr" rid="ref14">16</xref>
          ]). Through the described workflow a data set of
citizen needs and corresponding discussions is created, visualized to different parties
and made available for collaborative analysis and social interaction around the shared
visualization. The basis for the visualization is provided by collaborative
usergenerated data sets (citizen needs in the first-iteration prototype), which are then
integrated with external open data sets (municipal data in the second system design).
        </p>
      </sec>
      <sec id="sec-3-2">
        <title>3.2 Visual System Design and Protoype Implementation</title>
        <p>
          The main hypothesis of the system concept is that centering the interaction around a
shared visualization can further collaboration between the two stakeholder groups.
For this reason a central element of the user interface both for citizens and municipal
officials is a visual map of the citizen needs dataset contextualized by geographic
location (Google Maps). The map is practically permanently present and accompanies
the vast part of information access, interaction and discussion (e.g. see request input,
overview and detail pages in Fig 1). While citizens and the municipal officials are
likely to use the map for different purposes (e.g. entering requests, finding out what is
going in one’s neighbourhood for citizens vs. monitoring areas with intense citizen
activity or comparing needs with planned municipal actions), the map represents a
shared context of reference around which the communication between their different
perspectives can occur. Thus, the map implements a kind of a “boundary object”,
providing an important mechanism for collaboration in heterogeneous settings [
          <xref ref-type="bibr" rid="ref8">8</xref>
          ][
          <xref ref-type="bibr" rid="ref7">7</xref>
          ].
        </p>
        <p>
          At the same time, to cater for the distinctive needs of the two very different groups
of users the E-Local system has been designed as a multi-perspective information
system from its outset. The system design involves two different views on the user
data and the corresponding user interfaces: one for the citizens and one for the
municipal officials. While the basic functionalities and the GoogleMaps visualization
are available to both groups, the municipal officials have access to an additional
instrument, the CityCockpit. The primary means of visual exploration and
information access for the citizens is provided by the Google Maps visualization that
allows them to quickly spot and get information about relevant citizen requests in
their neighborhood. The main design assumption here has been that “locality” is the
primary measure of relevance for the citizen’s perspective. In contrast, based on
requirements interviews with municipal representatives, the primary means of access
for the municipal officials has been conceived in terms of a monitoring and control
center with an event ticker, statistical reports and visual charts for aggregated analysis
of citizen requests in addition to the GoogleMaps visualization. The described
1 To this end the E-Local platform interfaces with the online donation platform betterplace.org.
delineation of perspectives in the user interface implements the second important and
theoretically grounded requirement for supporting collaboration between
heterogeneous groups of users: the availability of means for the users to work within
their own distinctive perspective corresponding to their own terms, interests and
frames of reference (perspective making) [
          <xref ref-type="bibr" rid="ref1">1</xref>
          ]. Such a combination of separate user
interfaces with distinctive perspectives and a shared visualization (Google Maps) used
by both groups implements the model of perspective making and perspective taking:
while working in own interfaces allows the expression of distinctive perspective of
each group (perspective making), the map as a boundary object connects the two
perspectives thus supporting the discovery of relationships between them (perspective
taking), without forcing any group to abandon their own perspective.
        </p>
        <p>
          To implement the described model in practice, the system architecture allows easy
implementation and linking between different views on available data sets through a
MVC-like architecture and considers the conceptual multi-perspective visualization
model proposed in [
          <xref ref-type="bibr" rid="ref5">5</xref>
          ]. The prototype system implements the described use case and
functionalities based on the Django web application framework with a mysql
database. The frontend application is realized with Ajax and the mobile application is
an Android App. The system architecture is designed in a modular way with APIs
allowing easy integration of new data sets. In order to quickly realise a functioning
version of the system that can be tested and iteratively extended in practice, the
firstiteration protoype system implements a basic version with the communication and
data collection module alongside with the basic visualization mode (geo-localization
view) and basic social analysis functions (comments and discussions). The
preliminary CityCockpit has been provided at the level of a visual mockup,
illustrating basic reporting and analysis functionalities for municipal officials (Google
Maps visualization, new requests ticker, filtering of requests by topic, requests
pending answers, chart of citizen requests distribution by topic). Such implementation
allowed us to elicit feedback from target users in early formative tests and stakeholder
workshops with a cooperating municipality in order to verify the described design
decisions and assumptions before proceeding to final realization.
        </p>
      </sec>
      <sec id="sec-3-3">
        <title>3.3 Lessons from Formative Evaluation and Stakeholder Workshops</title>
        <p>A formative evaluation of a first-iteration E-Local prototype has been undertaken with
5 participants representing the citizen users. The participants were roughly equally
spread by age and sex within two demographic groups (two aged 24-26, three aged
50-56; two male and three female participants) and within a range of professional
backgrounds (fashion design, public administration, consulting, electric technician).
Most of them were regular Internet users (four participants between 0,5-7 h/day) and
highly proficient in computer use (three out of five) with three of them using one of
the well-known social networks. The participants were provided with access to the
web application with the basic functionalities implementing the typical E-Local use
case as depicted in Fig. 1 (submitting a request, extending the request, displaying
requests on a map, searching for requests, setting up user profiles, submitting
comments, going through the 3-phase cycle of the online discussion). They were
asked to complete a set of typical tasks corresponding to this use case and received no
prior training with the prototype. User feedback was collected through a Likert-scale
questionnaire. Table 1 depicts the main results of relevance for this paper.</p>
        <p>On one hand, the results suggest the suitability of the overall concept and the
ELocal prototype with largely positive to very positive responses to the individual
functionalities2. They are likely to be partially biased due to the fact that most
participants were highly proficient in using computers and the Internet on a daily
basis. However, this bias is partly offset by the fact that such users tend to represent a
typical core group of users in community-based portals. On the other hand, positive to
very positive responses to the overall construction of the web prototype, the clarity of
interaction design and the central role of visualization suggest that the described
principles of the system design and the central role of visualization resonate positively
with the target users. In particular this relates to the use and permanent presence of
the map as a central element for structuring navigation, interaction and collaboration.
All test participants rated the usefulness and importance of the map as a central
interaction element high or very high (Table 1, upper center, rows three and four). In
addition, four out of five users confirmed that their primary mode of use would be to
continuously monitor the activities in their local area and participate accordingly
(Table 1, bottom right, row three). This supports the design decisions of choosing
“locality” as the primary concept for modeling the citizen’s perspective (citizen
requests dataset) and choosing the map as a central element for mediating interaction.
2 The only exception is the 3-phases workflow model that hasn’t quite convinced and was
perceived neutrally (three users) or as cumbersome (two users; Table 1, row two). This
requires further investigation into the exact reasons for such perception.
The results thus indicate that the described requirements and design assumptions for a
multi-perspective visualization interface and data-centred visual interaction model
could be well suited for such a user group.</p>
        <p>
          As none of these test users provided free comments on the questionnaire, we
undertook an additional informal focus group with five additional participants to get
more contextual feedback. These participants were recruited among trainees and
employees of the Humboldt-Viadrina School of Governance who were not directly
associated with the project. They undertook the same tasks as the previous group but
provided only informal feedback. While the general feedback on the overall concept
and usability of the prototype largely corresponded to the above results, several
remarks provided a more differentiated picture. In particular, this includes a more
critical stance towards the explicit 3-phase model with automatic transition
constraints (“What if I would want to finish a phase earlier, because I feel to have
enough supporters for my issue?”) and the use of the number of supporters as
representative for the importance of an issue (incidentally, the same issue was raised
later on by the municipal officials). With respect to the visualization model, the most
interesting observation was the request to provide the same kind of analysis and
reporting tools foreseen for the municipal officials also to the citizens (“Why is the
CityCockpit intended only for the municipal administration and not for citizens? I
would like to be able to see the statistics and visual charts too. Especially, if they tell
me how the money spent by the administration is related to my needs.”) Another
participant inquired about the possibility to provide information about already
planned actions of the municipal administration for a given area so as to avoid
duplicate requests (“I would like to know what the municipal administration has
already planned to do in my area so I don’t need to waste time on entering requests
which will be resolved anyway”.). This feedback suggests that the visualization of the
municipal perspective should not be considered only in its own right but in relation to
the citizen’s perspective as well. Incidentally, this is a nice illustration of how the
theoretical requirements of the “perspective making – perspective taking” model [
          <xref ref-type="bibr" rid="ref1">1</xref>
          ],
are confirmed in practice: while the voicing of the citizen perspective (perspective
making) is important in its own right, there is also a need to put this in relation to a
visible municipality perspective, which needs to be understood by the citizens as an
orientation for their action (perspective taking).
        </p>
        <p>The feedback of the municipal administration was elicited in a stakeholder
workshop with municipal officials of the cooperating municipality (a town of approx.
60,000 inhabitants). The workshop involved 10 participants: the heads of the
administrative departments (“Dezernenten”) and their senior staff, the coordinator for
interdepartmental projects, the communications officer (also in charge of the internet
strategy) and the head of IT. As the basis for the discussion, after an introductory
presentation the prototype system was presented in a live-demo by replaying a
scenario for a typical use flow on the citizen-side and on the administration-side. This
included the CityCockpit in form of a visual mockup (features as stated in Section
3.2). The main findings of this workshop are summarized in Table 2.
Feedback Requirement
Increase the system usefulness by making visible what Provide a clear visualization of
the administration already does for the citizens. the administration perspective.
Support the discovery of relationships between citizen Support discovery of relations
requests and current municipal actions (e.g. repairing between visualizations of
street holes in winter; planning construction measures) – different perspectives.
for the officials and for the citizens (!)
Provide mechanisms for assessing the relevance of Support interactive
citizen needs by criteria other than number of supporters. parameterization of visualizations
Tools for monitoring and analysis must make existing Integrate visualization and
work easier, not adding additional workload (“Who will analysis closes with existing tasks
analyse all this data?”, “We have enough to do”). and processes.</p>
        <p>Overall the results can be summarized as follows: while gathering and visualizing
citizen needs was considered useful by some participants (e.g. the department of
construction), the majority of municipal officials felt that in order to become useful
for them, the system needs to more actively support the communication of actions that
the administration performs for its citizens (see Table 2). The CityCockpit should also
provide an easy analysis of the relative importance of citizen needs in comparison to
each other and to existing (or planned) budgetary actions as well as to the available
budget for specific areas or topics. Moreover, it should make clear these relations to
the citizens, not only the administration (with the expected effect of reducing the
number of generated citizen requests). Finally, all participants shared the concern that
functions for activity monitoring and data analysis must make existing work easier
instead of adding additional workload (reflecting the basic worry regarding the
introduction of the system in practice). In terms of requirements, this points to the
need to support the visualization of their own perspective for each group of users
(citizens vs. officials) while at the same time making it perceivable for the other and
providing easy-to-use ways for discovering relationships between them. Such results
(alongside with previously discussed citizen evaluation) led to a complete redesign of
the CityCockpit mockup and the associated multi-perspective visualization model for
social data analysis that are presented in the next section.</p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>4 The Open City Cockpit</title>
      <p>The results of formative user evaluation and workshops led to a complete redesign of
the City Cockpit. The main focus has been the development of a multi-perspective
visualization model, which would satisfy both the needs of the municipal officials and
the citizens while supporting collaborative data analysis between the two groups. This
resulted in a visualization design that extends existing approaches to social data
analysis and is grounded both in theory and in requirements elicited from practice.</p>
      <sec id="sec-4-1">
        <title>4.1 Visualising Multiple Perspectives</title>
        <p>The new design of the Open City Cockpit is depicted in Fig. 3. One shared user
interface provides a unique point of access for all users, regardless of affiliation
(citizens vs. officials). Within this interface any user can choose any of the available
perspectives to be displayed in one of the available visualization types. The current
design includes two main visualization types: a geographic map based on Google
Maps (Fig. 3, left) and a tree map visualization (Fig. 3 right). A perspective is now
represented by the corresponding data set (citizen needs dataset vs. municipal budget
dataset) and a selected visualization type. To satisfy the need of both supporting
working within one’s own perspective as well as facilitating the discovery of
relationships between the perspectives, the user can choose between three different
modalities of display: a one monitor view, a two monitor view and a mixed monitor
view. One monitor view displays only one perspective of the selected visualization
type. In the two monitors view (Fig. 3, right) the selected perspectives are displayed
next to each other (each in a selected visualization type) and are independently
controlled (e.g. zoom, filter, select). In the mixed monitor view, the two selected
perspectives are superimposed upon each other, whereby the portion of the space
occupied by each and the transparency of the superposition can be interactively
adjusted through movable sliders (Fig. 3, left). The visualization of both perspectives
is manipulated with a single control (e.g. zooming in on one, is automatically
followed in the other). For all visualizations, the data sets corresponding to a given
perspective are colour coded: green for citizen data, blue for the municipal data set.
By choosing a geographic visualization of the citizen data and of the municipal
budget in a mixed monitor view, both the citizens and the officials can easily
determine which budgetary actions are planned in their area (blue icons) and compare
this to related citizen requests (green icons). Similarly, by selecting a tree map
visualization of the municipal budget and of the citizen needs in a two monitor view it
is easy to compare the relations between expenditures in the budget (blue squares) to
relations between the number of citizen requests in related topics (green squares).</p>
      </sec>
      <sec id="sec-4-2">
        <title>4.2 Interfacing visualization and discussion</title>
        <p>
          The social analysis of the visualizations follows the principle of doubly-linked
discussions proposed in recent work [
          <xref ref-type="bibr" rid="ref4">4</xref>
          ][11]. A currently displayed visualization state
can be saved in form of a visual bookmark that can be recalled from the bookmarks
panel at any given time (Fig 3., rightmost column in both interface designs). User
comments are linked to the current state of the displayed visualization, unless the user
manually overrides this and specifies it more precisely: by assigning a specific item
(citizen request, budgetary action) to the comment or selecting an already saved visual
bookmark as its point of reference. In this way, a more precise and natural referencing
between comments and visualizations can be realized (e.g. a user may inspect several
visualizations or different zoom levels before reaching a conclusion which may relate
to one of the previous visualizations or a specific citizen request which spurred his
interest in the first place). Selecting a comment then displays a pop-up with the
corresponding visualization state and upon user confirmation switches the current
view to this particular visualization. In case a single item has been referenced, then
the corresponding visualization state highlighting this specific item is displayed. The
same holds in reverse, selecting a visualization state displays a list of comments
referencing it, while selecting an item highlights the referencing comments (Fig. 3,
comments panel).
        </p>
      </sec>
      <sec id="sec-4-3">
        <title>4.3 Implementation</title>
        <p>
          We are currently working on implementing the main elements of the described
visualization model and interface design in form of interactive prototypes that can be
used for the next user evaluation cycle. For the implementation of the tree map
visualization we are using an open source library from the javascript information
visualization toolkit [
          <xref ref-type="bibr" rid="ref15">17</xref>
          ]. The data sets for the municipal budget at this stage are
based on open data sources adhering to the JSON standard. The implementation of the
application state bookmarking (visual bookmarks) will follow the model of
URLbased state vectors proposed in [11]. In a further stage the data from the cooperating
municipality will be integrated into the prototype.
        </p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>5 Conclusions</title>
      <p>The presented analysis and first experiences in designing a visual system for social
data analysis in open government applications suggest that the heterogeneity of this
setting requires considering and integrating specific requirements and design
principles from collaboration theory and empirical practice. The first experiences in
the development and formative evaluation of a possible solution based on
multiperspective visualization point to the need for further investigation of
applicationoriented design principles in this emerging field of research.</p>
    </sec>
    <sec id="sec-6">
      <title>Acknowledgements</title>
      <p>Stephan Breidenbach has initiated the E-Local project and contributed important ideas
to the early concept of a participatory citizen platform. Martin Schneider implemented
the basic version of the first prototype and Oliver Frueauff and Annekathrin Wilke
provided valuable support in technical and organizational project coordination.</p>
    </sec>
  </body>
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