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  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>September</journal-title>
      </journal-title-group>
    </journal-meta>
    <article-meta>
      <title-group>
        <article-title>On the Importance of Context: Privacy Perceptions of General vs. Health-specific Data in Health Recommender Systems</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Laura Burbach</string-name>
          <email>burbach@comm.rwth-aachen.de</email>
          <email>burbach@comm.rwth-aachen.de belavadi@comm.rwth-aachen.de halbach@comm.rwth-aachen.de RWTH Aachen University Aachen, Germany</email>
          <xref ref-type="aff" rid="aff2">2</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Health Recommender Systems; Privacy; User Perceptions; Trust;</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Nils Plettenberg</string-name>
          <email>plettenberg@comm.rwth-aachen.de</email>
          <email>plettenberg@comm.rwth-aachen.de nakayama@comm.rwth-aachen.de kojan@comm.rwth-aachen.de calero-valdez@comm.rwth-aachen.de RWTH Aachen University Aachen, Germany</email>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Acceptance; Application contexts</institution>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Johannes Nakayama</institution>
          ,
          <addr-line>Lilian Kojan</addr-line>
          ,
          <country>André Calero Valdez</country>
        </aff>
        <aff id="aff2">
          <label>2</label>
          <institution>Poornima Belavadi</institution>
          ,
          <addr-line>Patrick Halbach</addr-line>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2020</year>
      </pub-date>
      <volume>26</volume>
      <issue>2020</issue>
      <abstract>
        <p>Recommender systems are essential to reduce complexity on the web due to the plethora of available content. However, depending on design choices they require a lot of (potentially personal) data to work, raising the issue of privacy and acceptance of such systems. This is particularly true when they are used in sensitive matters such as health. We addressed these issues in a survey of 163 participants in which we presented three diferent health-related contexts where recommender systems can be used: 1) desire for better nutrition and more exercise, 2) information about causes and treatment of headaches and nausea, and 3) information about side efects of a medication prescribed by a doctor. We found that participants are generally more willing to disclose their general data than their specifically health-related data. The more health-critical the context of use was, the more willing they were to disclose health-related data.</p>
      </abstract>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>CCS CONCEPTS</title>
      <p>• Human-centered computing → Human computer interaction
(HCI); Collaborative and social computing; Empirical studies
in collaborative and social computing; • Security and privacy →
Social aspects of security and privacy.</p>
      <p>HealthRecSys ’20, September 26, 2020, Online, Worldwide
© 2020 Copyright for the individual papers remains with the authors. Use permitted
under Creative Commons License Attribution 4.0 International (CC BY 4.0). This
volume is published and copyrighted by its editors.</p>
    </sec>
    <sec id="sec-2">
      <title>INTRODUCTION</title>
      <p>
        Many people use the Internet to seek health-related information
before or after a doctor’s appointment [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]. However, such information
is often complex and contradictory which makes it dificult for users
to assess it along with its relevance to their personal situation [
        <xref ref-type="bibr" rid="ref26">26</xref>
        ].
Recommender systems tackle this issue by filtering information and
ofering personalized recommendations to users [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]. Such system
can also be used in the healthcare sector to recommend information,
therapies, or side-efect free medicine [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ]. While recommender
systems are already more established and accepted in many other areas
of application, (potential) users of health recommender systems are
even more concerned about privacy and security. User acceptance
is hampered by technical aspects such as data ownership or privacy
and security, as well as user diversity aspects such as data and
health literacy [
        <xref ref-type="bibr" rid="ref29 ref8">8, 29</xref>
        ].
2
      </p>
    </sec>
    <sec id="sec-3">
      <title>RELATED WORK</title>
      <p>
        Health recommender systems can improve the quality of preventive
health care [
        <xref ref-type="bibr" rid="ref24">24</xref>
        ]. Nonetheless, when asked about their inclination
to disclose data to these systems, users are often concerned about
their privacy and these concerns must be taken into account when
considering acceptability [
        <xref ref-type="bibr" rid="ref18">18</xref>
        ].
      </p>
      <p>
        Li et al. investigated the acceptance of wearables in the health
sector and found that users conduct a risk-benefit analysis to decide
whether to use wearables: If the perceived benefit outweighs the
perceived risk, they are more likely to use them [
        <xref ref-type="bibr" rid="ref15">15</xref>
        ]. The
phenomenon of users performing a risk-benefit analysis to decide which of
their personal information they want to disclose is called Privacy
Calculus [
        <xref ref-type="bibr" rid="ref14 ref3">3, 14</xref>
        ]. For this risk-benefit analysis, it has been shown
that patients who use computers more frequently [
        <xref ref-type="bibr" rid="ref21">21</xref>
        ], use the
Internet more often, or have a higher level of education are more
willing to disclose data to obtain a benefit.
      </p>
      <p>
        Caine and Hanania have investigated which type of health data
users voluntarily disclose [
        <xref ref-type="bibr" rid="ref7">7</xref>
        ]. They found that users are less willing
to disclose more sensitive health data such as information on their
mental and sexual health. In contrast, Frost et al.’s analysis of online
cancer communities found that patients afected by poorer health
were more willing to disclose their private data [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ].
      </p>
      <p>
        In addition to the sensitivity of the data itself, it has been shown
that other experiences on the Internet afect the willingness to
disclose data as well. Awad and Krishnan found that a previous
invasion of privacy decreased the respondents’ willingness to be
profiled for personalized advertising [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]. Similarly, Frost et al. found
that patients who previously had bad experiences on the Internet
were less willing to disclose their data [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ].
      </p>
      <p>
        When considering user preferences, technology acceptance
models are also relevant. Research of technology acceptance has shown
an influence of user factors such as gender, age, and technology
selfeficacy on the willingness to use a technology [
        <xref ref-type="bibr" rid="ref27">27</xref>
        ]. Further, when
asked to provide personal data to an Internet service provider [
        <xref ref-type="bibr" rid="ref23">23</xref>
        ],
users difer in their perceptions of trust [
        <xref ref-type="bibr" rid="ref17">17</xref>
        ] and privacy
concerns [
        <xref ref-type="bibr" rid="ref16 ref20 ref32">16, 20, 32</xref>
        ].
      </p>
      <p>
        Some studies have shown that a majority of respondents (patients
and doctors) gave positive ratings to the use of computers for patient
health. For them, the advantages outweigh the disadvantages in
terms of confidentiality [
        <xref ref-type="bibr" rid="ref15 ref21">15, 21</xref>
        ].
      </p>
      <p>Nevertheless, the decision to use a health recommendation
system remains a balance between benefit and concern. Diferent
usage contexts may provide diferent benefits and result in diferent
concerns. Much of previous research has looked at specific
illnessrelated contexts (e.g., smoking cessation, weight loss, sports) or
specific privacy concerns in isolation.</p>
      <p>Our Contribution. The objective of this study is to consider the
privacy concerns (potential) users have when using
recommendation systems in diferent health application contexts, and the extent
to which they are willing to disclose diferent general and health
data. In this study, we identify what general and health data the
participants consider to be sensitive and whether there are
diferences in the willingness of participants to disclose more sensitive
data. We also consider whether diferent user factors influence the
willingness to disclose the aforementioned data.
3</p>
    </sec>
    <sec id="sec-4">
      <title>METHODS</title>
      <p>To find out whether the application context of health
recommendation systems influences the users’ willingness to disclose their
data, we conducted an online survey in German. Participants were
acquired using convenience sampling between July and August
2018 and March and April 2019. The survey was distributed via the
social network Facebook using snowball-sampling.</p>
      <p>The survey consisted of three parts: First, we asked the
participants for demographic factors (age and gender), perceived health,
and smoking habits. Next, we measured technology self-eficacy ,
health concerns, privacy concerns, institution-based (dis)trust and
disposition to trust. Lastly, we assessed the participants willingness
to disclose personal and health data for three diferent application
contexts.</p>
      <p>
        Technology Self-Eficacy (TSE) . We used eight items of Beier’s
scale for measuring technology self-eficacy (TSE) [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ], extended by
two additional items to account for the shift in answering tendency.
Internal reliability was good according to DeVellis [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ] (Cronbach’s
 = .82).
      </p>
      <p>Health concerns. To assess participants’ general health
concerns, we asked them four questions about whether they were
worried about their general health status, that they might develop
a chronic disease, that they might fall in with a serious illness or
that they get infected when sick people are in their environment
(Cronbach’s  = .807).</p>
      <p>
        Privacy concerns. Perceived privacy while using Internet
services was assessed with seven items from Xu et al., Li et al. and
Morton et al. [
        <xref ref-type="bibr" rid="ref16 ref20 ref32">16, 20, 32</xref>
        ]. The items measure generalized fear that
general data stored online could be “insecure” and concerns about
misuse of personal data (Cronbach’s  = .777).
      </p>
      <p>
        Trust. To assess institution-based trust, we used six items from
McKnight et al. [
        <xref ref-type="bibr" rid="ref17">17</xref>
        ]. Through principal component analysis we
discovered that the scale breaks down into two dimensions. The
ifrst dimension depicts users’ trust in online services concerning
the handling of their (personal data) (Cronbach’s  = .617). The
second dimension assesses how much users trust the technical
infrastructure to ensure privacy on the Internet (technical)
(Cronbach’s  = .862). In addition, we measured general disposition to
trust using six items by McKnight [
        <xref ref-type="bibr" rid="ref17">17</xref>
        ] (Cronbach’s  = .732).
      </p>
      <p>Application contexts. In the last part of the survey we presented
three diferent application contexts of recommendation algorithms
in health settings to the participants. For twelve diferent types
of data, such as date of birth or medication currently being taken,
we asked whether the participants would disclose these in each
application context.</p>
      <p>First, the participants should imagine that they committed to a
healthier lifestyle (context healthy life). We explained that the health
recommendation system is a mobile app that provides nutritional
recommendations and encourages users to be more active.</p>
      <p>For the second application context (complaints) the participants
should imagine that they feel headaches and nausea and therefore
use an app to find out about the causes and treatment options. They
were told that the more data they would enter, the more reliable
the diagnosis would be.</p>
      <p>In the last application context (drugs) the participants should
imagine that the doctor prescribes a medication for them and they
would like to check with an app which side efects can occur. They
were told at this point that the more data the app receives, the more
reliably it can assess the risks.</p>
      <p>For all three contexts, we performed a factor analysis with the
12 diferent data items, resulting in two scales, general data (Date
of Birth, Gender, height, weight) and health data (preexisting
conditions, chronic illnesses, illnesses of family members, allergies,
current medication, information about diet, alcohol consumption,
smoking behavior). We then tested the reliability of the two scales
for each context individually as shown in table 1.
3.1</p>
    </sec>
    <sec id="sec-5">
      <title>Hypotheses</title>
      <p>Following the results of the study of Caine and Hanania (see
section 2), we assume for all contexts that the participants are less
willing to disclose health data, which should be more sensitive to
them than general data (1). We also assume that, according to the
risk-benefit analysis, participants distinguish between the three
application contexts and are more willing to disclose their data
for the context drugs, as this is where they could see the strongest
benefit—preventing potentially dangerous side-efects( 2).</p>
      <p>We further assume that negative experiences with the Internet
and thus higher privacy concerns (3) and lower institution-based
trust (4) inhibit the willingness to disclose data, while the
disposition to trust boosts it (5). Lastly, we assume that higher age (6),
lower Technology Self Eficacy (7), and being female (8) correlate
with a lower willingness to disclose data.
3.2</p>
    </sec>
    <sec id="sec-6">
      <title>Statistical Procedures</title>
      <p>
        To analyze our descriptive results we used means, standard
deviations, and 95% within-subject confidence intervals [
        <xref ref-type="bibr" rid="ref19">19</xref>
        ]. We ensured
sampling adequacy by using the Kaiser-Meyer Olkin criterion. With
Bartlett’s  2 test we tested the sphericity of our data. We further
looked at associations between variables using Pearson
correlations. We report the correlation coeficient  and an asymmetric
95% confidence interval that is generated by population
bootstrapping [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ]. Finally, we used MANOVA repeated measurements to
analyze diferences between the contexts.
      </p>
      <p>All study materials, data, and analysis code are available online
at the Open Science Foundation.1
4</p>
    </sec>
    <sec id="sec-7">
      <title>RESULTS</title>
      <p>
        We analyzed the data using R version 3.6.2 and several packages [
        <xref ref-type="bibr" rid="ref2 ref22 ref25 ref28 ref30 ref31">2,
22, 25, 28, 30, 31</xref>
        ]. Analyses were run on Mojave 10.14.6 MacOs
(system x86 64, darwin 15.6.0). Our data showed good sampling
adequacy using the Kaiser-Meyer Olkin criterion ( &gt; 0.8 for
all items) and showed suficient sphericity. With Bartlett’s  2 test
we tested the sphericity of our data ( 2 (630) = 7008.197,  &lt; .001),
which was present. Next, we will describe our sample and then
present the findings of our analyses.
4.1
      </p>
    </sec>
    <sec id="sec-8">
      <title>Description of the sample</title>
      <p>Of the 163 participants 108 (66%) were female and 55 (34%) were
male. The participants were on average M = 28.8 years old (SD =
11.1). Most participants in our sample did not smoke (145, 89%). Men
and women were about the same age on average ( (161) = −0.695,
 = .488). The participants showed a rather low technology
selfeficacy (M = 3.20, SD = 0.80) and rather low health concerns (M
= 3.14, SD = 1.18). They showed an even lower institution-based
trust technical (M = 2.74, SD = 1.06) and matching this rather high
privacy concerns (M = 4.21, SD = 0.06) and a rather high
institutionbased distrust personal data (M = 4.41, SD = 1.08). Interestingly they
showed a rather high disposition to trust (M = 3.89, SD = 0.70).</p>
      <p>Correlations of independent variables To get a more accurate
impression of our sample, we can look at the Pearson correlations
of our independent variables (see Table 2). Older people have a
1Link to the OSF Repository:https://osf.io/5f6jy/
lower general disposition to trust as well as a higher
institutionbased distrust personal data. Participants with a higher computer
self-eficacy have also higher privacy concerns. Higher computer
self-eficacy and higher privacy concerns also correlate positively
with a higher institution-based distrust personal data. Interestingly,
participants with higher privacy concerns have also more
institutionbased trust technical. Participants with a higher institution-based
trust technical tend to have a lower disposition to trust.</p>
      <p>Application contexts As described in section 3, we presented
three application contexts of health recommendation systems to
the participants and asked if the participants would disclose their
personal and health data. Figure 1 shows, that the participants
indicated for each context a higher willingness to share their general
data than their health data. The highest diference occurs for a
healthy life.</p>
      <p>Means of the willingness to disclose data for the three contexts</p>
      <p>Comparing the three contexts, we found that participants are
less willing to disclose their general data for complaints and most
willing to disclose their general data for a healthy life. In contrast,
they are less willing to disclose their health data for a healthy life
and most willing to disclose their health data to find side-efects of
drugs. The more sensitive the use context (most to less sensitive:
drugs, complaints, healthy life), the more willing they are to disclose
health data.</p>
      <p>A computed MANOVA for repeated measurements with the
three contexts and the general data showed a significant overall
efect of the contexts (  Λ = .754,  (2, 143) = 23.33,  &lt; .001)
with a large efect ( Partial 2 = .246). Gender is not related to
willingness to disclose general data (˜2 = 31.68 − 34.66,  &gt; .05).
We also found a significant overall efect of the contexts for health
data ( Λ = .807,  (2, 143) = 17.08,  &lt; .001) with a large efect
(2 = .193). The ˜2-Test showed a small efect of gender
on the drugs context (˜2(16) = 26.40 − 18.00,  = .049), females
are more willing to disclose their health data (M = 3.92, SD = 1.01)
than males (M = 3.46, SD = .20). Gender did not relate to the other
contexts (˜2 = 11.27 − 18.00,  &gt; .05).</p>
      <p>So far, we looked at the overall willingness to disclose both
general and health data in the three contexts. Following, we look
at the willingness to disclose the (12) individual data types. As
mentioned before and as can be seen in Figure 2, the participants’
willingness to disclose data is higher for general data than for health
data. From the general data, the participants are less willing to
disclose their day of birth. This applies to all contexts, but for
a healthy life the contrast between the participants’ willingness
to disclose their personal and health data is clearer. In particular,
the participants are less willing to disclose hereditary diseases
and medicine intake for a healthy life, whereas they are willing to
disclose their medicine intake for the drugs context. Looking at the
health data, the participants are for all contexts more willing to
disclose eating habits, sleeping data and activity data. In contrast,
they distinguish between the contexts for pre-existing conditions,
chronic diseases, hereditary diseases, allergies and medicine intake.
For the context drugs, they are strongest inclined to disclose the
most types of health data, followed by the context complaints and
they are least willing to disclose the data for a healthy life.
Means of the willingness to disclose data for all data types
Healthy life
● ● ● ● ● ●</p>
      <p>● ●● ● ● ●
Complaints ● ● ● ● ● ●
● ● ● ● ● ●</p>
      <p>Drugs
day of birth
gender
height
weight
taapre−existing conditions
fd chronic diseases
eo hereditary diseases
yp allergies
T medicine intake
eating habits
sleeping data
activity data
1</p>
      <p>2 3 4
Willingness to disclose data
5
Data category ● ● general data</p>
      <p>Beyond the efect of the diferent application contexts and
diferent types of data we found that higher health concerns are associated
with a higher willingness to disclose general data for all three
contexts (healthy life:  = −.19,  = .018; complaints:  = .20,  = .018;
drugs:  = .19,  = .019) and their health data for context healthy
life ( = .18,  = .028). Further, disposition to trust causes the
participants to be more willing to disclose their health data for a healthy
life ( = .22,  = .007). We did not find an influence of age,
computer self-eficacy , privacy concerns and institution-based trust on
the willingness to disclose any data (all  &gt; .05). Looking at the
diferent data types in the three contexts, participants that are more
willing to disclose any data for any context are also more willing
to disclose other data or for other contexts (all  &gt; .47,  &lt; .001).
5</p>
    </sec>
    <sec id="sec-9">
      <title>DISCUSSION</title>
      <p>In this study, we investigated the efects of three diferent
application contexts for health recommendation systems and the efect
of user diversity factors on the willingness to disclose personal
and health data. We first state, that participants diferentiate
between personal and health data and are more willing to disclose
their general data (1 √). Furthermore, the diferent contexts had a
significant influence on the willingness to disclose. For health data,
our results show that the more sensitive the application context is,
the more willing the participants are to disclose their health data
(2 √). For general data, the participants prefer to disclose their
data for a healthy life, whereas they are least willing to disclose
data for complaints (2 X).</p>
      <p>
        From the investigated user-factors only health concerns and
disposition to trust (5 √) seem to influence the willingness to
disclose data. At this point, the increased concern about health
seems to increase the participants’ willingness to disclose their
data. People with better health status may expect fewer personal
benefits from disclosing their data [
        <xref ref-type="bibr" rid="ref13">13</xref>
        ]. We did not see a strong
efect of previous experience ( 3 and 4 X), age (6 X), gender (7
X) or technology self-eficacy ( 8 X).
      </p>
      <p>
        Participants had to think of a fictitious situation which can lead to
reports revealing less or more data than they would actually reveal.
Besides, it is conceivable that users of health recommendation
systems would change their initial willingness after experiencing
the benefits of the recommendation systems. Nevertheless, studies
in technology acceptance showed that preferences are at least to
some degree stable over time [
        <xref ref-type="bibr" rid="ref27">27</xref>
        ].
      </p>
      <p>In reality, users often do not consciously decide whether they
want to disclose their data but disclose their data unconsciously or
inadvertently. Nevertheless, our study shows that diferent
application contexts of health recommendation systems have an impact on
what data users want to disclose. In future research, we would like
to take up this point and use experiments to examine how users
actually perceive the recommendation systems in the respective
context.
5.1</p>
    </sec>
    <sec id="sec-10">
      <title>Does only the application context influence the acceptance of recommendation systems?</title>
      <p>
        Of course, more aspects that may influence the acceptance of
recommendation systems than the application context. Burbach et
al. [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ] for example investigated, if individuals accept five diferent
recommendation algorithms (content-based recommendation,
collaborative filtering, hybrid recommendation, social-, trust-based
recommendation) for three diferent product categories (books,
mobiles, and contraceptives). Critically, not only the purpose of the
recommendation but also the use of data inside of diferent
algorithms seems to play a role in the acceptance of recommendation
systems. Here, algorithms that are able to create a more accurate
picture of the users, were less likely to be accepted [
        <xref ref-type="bibr" rid="ref5">5</xref>
        ].
6
      </p>
    </sec>
    <sec id="sec-11">
      <title>CONCLUSION</title>
      <p>Concluding, many aspects determine how much individuals accept
recommendation systems. The acceptance of diferent
recommendation systems depends among other things on the application
context of the recommendations, but also on the product type that
is recommended. Our research has shown, that the users have a
very distinct idea of what type of data should be used in what type
of context and show decreased willingness if the data seems
unnecessary for a health-related decision. Accordingly, there is not a
one-size-fits-all recommendation system, but the acceptance of the
recommendation system is always determined by a combination of
diferent contexts and users.
7</p>
    </sec>
    <sec id="sec-12">
      <title>OUTLOOK</title>
      <p>In the future, we will conduct additional studies on the user
acceptance of recommendation systems. We will consider diferent
aspects in one study. For example, it would be interesting to
consider whether the application context or the recommended item
have a greater influence on the acceptance of diferent
recommendation systems and how these two aspects influence each other. A
particularly suitable method for this would be a conjoint analysis,
in which diferent aspects of a recommendation system could be
weighed against each other.</p>
    </sec>
  </body>
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            <given-names>Xu</given-names>
          </string-name>
          ,
          <string-name>
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          ,
          <string-name>
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          , and
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  </back>
</article>