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  <front>
    <journal-meta />
    <article-meta>
      <title-group>
        <article-title>Simulation-based Co-Creation of Algorithms</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Sebastian Dennerlein</string-name>
          <email>sdennerlein@know-center.at</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Dominik Kowald</string-name>
          <email>dkowald@know-center.at</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Viktoria Pammer-Schindler</string-name>
          <email>viktoria.pammer@tugraz.at</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Elisabeth Lex</string-name>
          <email>elisabeth.lex@tugraz.at</email>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Tobias Ley</string-name>
          <email>tley@tlu.ee</email>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Graz University of Technology, Institute of Interactive Technologies and Data Science</institution>
          ,
          <addr-line>Graz, AT</addr-line>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Know-Center GmbH</institution>
          ,
          <addr-line>Graz, AT</addr-line>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>Tallinn University, Institute of Informatics</institution>
          ,
          <addr-line>Tallinn, EE</addr-line>
        </aff>
      </contrib-group>
      <abstract>
        <p>Co-Creation methods for interactive computer systems design are now widely accepted as part of the methodological repertoire in any software development process. As the community is becoming more aware of the fact that software is driven by complex, artificially intelligent algorithms, the question arises what “Co-Creation of Algorithms” in the sense of end users explicitly shaping the parameters of algorithms could mean, and how it would work. Algorithms are not tangible like tool features and effects are harder to be explained or understood, especially in early design phases without a software prototype. Therefore, we propose a Simulation-based Co-Creation method that allows TEL researchers to collaboratively design algorithms with end users by creating user stories and personas, modelling assumptions and discussing simulated effects. The method extends the build &amp; evaluate loop of co-design iterations, even when the learning technology for the algorithm is not ready. Our proposal is a methodological idea for discussion in the EC-TEL community, yet to be applied in a practice.</p>
      </abstract>
      <kwd-group>
        <kwd>Co-Design</kwd>
        <kwd>Algorithms</kwd>
        <kwd>Personas</kwd>
        <kwd>User Stories</kwd>
        <kwd>Simulation</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>
        The Co-Creation of interactive computer systems design has been addressed in the
last decades. Methodological approaches such as Collaborative Design (Co-Design)
and Design-based Research
        <xref ref-type="bibr" rid="ref2">(DBRC, 2003)</xref>
        suggest the iterative creation of the design
artefact with all stakeholders via successive prototyping. This also applies to the
CoCreation of Algorithms, but corresponding methods are missing. TEL researchers
cannot leverage the same methods as for tools. For instance, algorithms can not be easily
visualized in paper prototypes; their effects can only become partially visible in
enacting a complex human-computer interaction with a paper prototype, which is
cumbersome and not expressive enough. As algorithms are not tangible per se, their co-creation
is more complex than co-creating learning tools. First, they can only be experienced
when their interface to the user, i.e. the corresponding learning technology, is
implemented and live. And due to the necessity of user interactions, second, they often need
time to show their effect in practice (e.g., facilitating consensus building in social
tagging systems).
      </p>
      <p>Designers of algorithms, however, need early and informed input from the target
domain, so they do not lag behind the co-creation of the learning technology and do not
follow wrong assumptions. Therefore, the open research question is: “How can
algorithms be collaboratively designed for end users’ needs so that the impact of the
algorithm is easy to assess, especially in early phases of co-design without implementation
in a live system?” We propose agent-based simulations for the co-creation of algorithms
with end users to represent effects of algorithmic design decisions in a tangible manner
before software prototyping. The proposed method extends the build &amp; evaluate-loop
of a co-design iteration by co-creating personas and user stories in each iteration that
then serve as input for modelling the simulation.
2</p>
    </sec>
    <sec id="sec-2">
      <title>Background and Related Work for Agent-Based Simulations</title>
      <p>
        Agent-based simulations are computational models for simulating the interactions
of autonomous agents and assessing their effects on each other and the whole system.
One example of an agent-based simulation model is the Naming Game model
        <xref ref-type="bibr" rid="ref1">(Baronchelli et al., 2006)</xref>
        . Here, agents are represented as nodes in a network that
interact at random. Nodes are equipped with so-called opinions and when two nodes
interact, they either agree on a common opinion or extend their set of opinions if there is no
common one. In the work of Hasani-Mavriqi et al. (2018), this model was used to easily
simulate millions of interactions and study opinion dynamics and to assess the impact
of various meeting rules (i.e., algorithmic parameters). Agent based simulations have
also been used, for example, to study how recommendations are accepted by users
        <xref ref-type="bibr" rid="ref6">(Saga et al., 2013)</xref>
        . The latter is also used in the recently started European project CPN
(https://www.projectcpn.eu/) to evaluate news recommendations.
3
      </p>
    </sec>
    <sec id="sec-3">
      <title>Co-Designing an Algorithm using an Agent-Based Simulation</title>
      <p>
        Co-Creation of Algorithms follows the known routines of a co-design iteration, i.e.
the build &amp; evaluate loop of stating assumptions in form of a (re-)designed prototype
and evaluating it in the field
        <xref ref-type="bibr" rid="ref5">(Ley et al., 2014)</xref>
        . First, researchers need to establish an
understanding of the domain. They can, for example, conduct a contextual inquiry to
understand stakeholders, working practices and context, the algorithm needs to be
codesigned for. This is reflected in user stories and personas for an abstract depiction of
the needs and characteristics of the domain as well as their end users. Both kinds of
design artefacts can be discussed and refined in each iteration. Personas are concrete,
virtual people who are part of the target user group of the desired system and represent
typical characters in abstract manner. They should not be thought of as a group as it is
easier to think about concrete people than groups
        <xref ref-type="bibr" rid="ref3">(e.g., Grudin &amp; Pruitt, 2002)</xref>
        . User
stories
        <xref ref-type="bibr" rid="ref7">(Thalmann &amp; Schäper, 2018)</xref>
        , on the other side, are abstractions of relevant
practices including software systems, where a co-designed artefact should help to
support or solve the design problem. They include the defined personas within their role,
reflect context as well as goal and depict interactions in a stepwise process of usage that
can be visualized.
      </p>
      <p>The acquired domain understanding then informs the (re-)design of the agents in
the simulation as well as the algorithm itself: e.g. while the user story explains the
circumstances and needs of the domain that inform the design of the algorithm, personas
represent its stakeholders and serve modelling the agents for the simulation. Our
proposal to use agent-based simulations, therefore, relies on the collaborative design
process of creating and elaborating personas and user stories with end users in each
codesign iteration. These design artefacts represent the core input to the iterative
development of the agent-based simulation. As an example, let us assume the development
of a novel recommender system. The user story suggests increased information sharing
leading to the selection of two algorithms: Algorithm 1 recommends popular items and
Algorithm 2 similar items as the ones the user has already interacted with. Let us
further assume that we have two kinds of personas: User 1 consumes mainly trustful and
agreed items and User 2 mainly novel items from her field of interest. These virtual
users define the agents. Now, Algorithm 1 (popular) should perform better for User 1
(trust) and Algorithm 2 (similar) better for User 2 (novel), with both contributing to
information sharing. With agent-based simulations, we can quickly assess such
assumptions in early co-design phases without the need of users testing the recommender
system live at that point in time. Furthermore, results of the simulation (evaluation) and a
respective visualization can be fed back to and discussed with end users to adapt the
algorithms (i.e., user stories) if they do not fit the virtual people (i.e., personas).</p>
      <p>The proposed process of co-creating algorithms with the help of agent-based
simulations as part of a co-design iteration is reflected in Figure 1. We do not pose any other
constraints on the co-design process, but simply assume in this paper that agent-based
simulations may provide systematic input to the iterative co-creation of algorithm as
part of (early) build &amp; evaluate-loops. This way, a partly functional “prototype” can be
implemented in form of a simulation representing a first draft of the algorithm. Based
on such a simulation, researchers and users can assess the performance of the algorithm
for the use case, even though there is no system available to implement the algorithm
yet. As well, making the algorithm and its effects “observable” builds the ground for
substantial discussions with end users allowing for revising the domain understanding
in terms of personas and user-stories, for example. The higher understanding of the
algorithmic impact may help (users) to find informed decisions, on the one hand, and
may benefit the shared understanding of the co-design team, on the other hand.</p>
      <p>We consider two further aspects of simulation-based co-creation of algorithms. In
the early co-design phases, clearly the algorithm itself is a rough proposal, which must
be wrong to a certain extent. This does not matter as insights are gained from wrong
design decision as well. In later co-design phases, the algorithm might already be usable
as part of a running system allowing the end users to “directly” experience it. Analysing
this real life-usage allows concretizing the domain understanding as well. Researcher
can analyse the logs, compare the understanding of the users in the logs with the
personas in the user stories as well as the agents in the simulation and update them.
Afterwards, assumptions about the needs for the algorithm can be trialled with the end users
by discussing the re-designed personas, user story and agent-based simulation. Hence,
simulations could be drawn upon as security measure before risking live tests and
potentially harming a running system; this becomes especially important when
considering increasing levels of integrating the learning tool into (working) practice
4</p>
    </sec>
    <sec id="sec-4">
      <title>Discussion and Outlook</title>
      <p>We propose to co-create algorithms by designing user stories and personas with end
users and respectively modelling agent-based simulations as part of each co-design
iteration. A crucial role is the design of agents allowing for the early evaluation of the
algorithm and getting usable insights before its implementation in the desired learning
technology. We leverage the method not only for assessment, but understand it as a
codesign method making algorithms tangible and researchable in a user- and
domainoriented approach, before a live system allows for that. This sheds light on the slightly
“occult” process of algorithmic development and contributes to the much-needed
conversation on how we ethically design these invisible decision-making instruments.</p>
      <p>For future work, we plan to further concretize the proposed model and apply it for
co-design of recommender algorithms in design-based research projects. It is also still
to be clarified, if and how this methodological idea goes along designing and evaluating
algorithms as part of a live system in later co-design phases</p>
    </sec>
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