<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Archiving and Interchange DTD v1.0 20120330//EN" "JATS-archivearticle1.dtd">
<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>Belgium
2 Independent Data Journalist</journal-title>
      </journal-title-group>
    </journal-meta>
    <article-meta>
      <title-group>
        <article-title>OpenTED Browser: Insights into European Public Spendings</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Yann-Ael Le Borgne</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Adriana Homolova</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Gianluca Bontempi</string-name>
        </contrib>
      </contrib-group>
      <abstract>
        <p>We present the OpenTED browser, a Web application allowing to interactively browse public spending data related to public procurements in the European Union. The application relies on Open Data recently published by the European Commission and the Publications O ce of the European Union, from which we imported a curated dataset of 4.2 million contract award notices spanning the period 2006-2015. The application is designed to easily lter notices and visualise relationships between public contracting authorities and private contractors. The simple design allows for example to quickly nd information about who the biggest suppliers of local governments are, and the nature of the contracted goods and services. We believe the tool, which we make Open Source, is a valuable source of information for journalists, NGOs, analysts and citizens for getting information on public procurement data, from large scale trends to local municipal developments.</p>
      </abstract>
      <kwd-group>
        <kwd>Public Procurements</kwd>
        <kwd>European Union</kwd>
        <kwd>Open Data</kwd>
        <kwd>Government Transparency</kwd>
        <kwd>Data Journalism</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>-</title>
      <p>
        Public procurement is the process whereby governments buy goods and services,
such as o ce supplies, equipment, buildings, roads, and so forth. It represents
about one third of total government expenditures in OECD countries [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ]. This
is usually a public-private deal in which the buyer is a public entity and the
(winning) bidder is usually a privately owned company. Public procurements
are mostly nanced by public funds [
        <xref ref-type="bibr" rid="ref11 ref7">7, 11</xref>
        ].
      </p>
      <p>
        The development of Tenders Electronic Daily (TED) [
        <xref ref-type="bibr" rid="ref9">9</xref>
        ] can be considered as
the biggest EU-wide e ort made so far to support procurement across borders.
TED, which is managed by the Publications O ce of the European Union [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ],
is the online version of the S Series of the O cial Journal of the European
Union (OJEU), which is a supplement to the Journal particularly focused on
European public procurement. TED publishes over 1000 new over EU-threshold
value procurement notices every day worth about EUR 400 billions a year [3{
5]. Furthermore, TED also publishes other documents coming from funds to be
spent on EU external aid and the procurement of EU institutions.
      </p>
      <p>Along with TED, the Publications O ce provides bulk downloads of its data.
The raw dataset contains all contract notices for tender data since 1995 in XML
format, and its size is around 100 GB (GigaBytes). The browsing and analysis
of this dataset raises a number of complex challenges, due to varying quality of
data between countries and years, missing values, variability in the naming of
contracting authorities and entities, multilingual documents, and so forth.</p>
      <p>
        The Directorate-General for Internal Market, Industry, Entrepreneurship and
SMEs (DG-GROW) of the European Commission has recently initiated great
e orts in the curation of the Publications O ce data, and released in August
2015 a summary of all contract award notices (CANs) for European public
procurements for the period spanning 2006-2015 [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ]. The curated dataset provides
an unprecedented source of information on public spending in the European
Union and yields very valuable information on procurement data. In
particular, it provides information related to the identity of contracting authorities and
contractors, the nature of the supplies/works/services, the nal contract values
and the number of o ers for a given contract notice. Such information not only
makes it possible to provide insights in the network of public/private
partnerships, but also to exhibit procurements patterns across all European countries,
or to detect (and avoid) corruption [
        <xref ref-type="bibr" rid="ref1 ref16 ref18 ref4">1, 4, 16, 18</xref>
        ].
      </p>
      <p>The relative large size of the dataset however still prevents its analysis from
users without an analytics background: Data is provided as CSV les for each
year of CAN (from 2006 to 2015, ten les in total), whose size ranges from
around 100 MB (MegaBytes) to 300 MB, totalising about 2 GB (GigaBytes).
While the size of the dataset can be stored without trouble on current laptop or
desktop con gurations, the opening of such les remains a challenge for standard
spreadsheet applications such as Excel, and makes analyses spanning multiple
years (i.e. ltering data from multiple les) very tedious. It must be stressed that
most of the people interested in CAN data (journalists, entrepreneurs, citizen,
...) do not have the necessary analytics background to explore datasets of such
size.</p>
      <p>The OpenTED browser aims at bridging this gap, and our contributions are
the following. First, data is stored on our OpenTED server, and does not need
to be fully downloaded, making it easier for users with slow Internet connection
to access the data. Users can furthermore lter the data they need (according to
countries, years, type of goods, and so forth), and download only what they are
interested in. Second, we provide a visualisation tool, based on Sankey diagrams,
that represents as a graph the contract awards between public authorities and
private contractors. The visualisation makes clear how much money the contracts
are worth, and provides hyperlinks to the o cial TED award notices for further
details. Finally, we make the code for both the data preprocessing (Python) and
the Web application (R Shiny) open source. A docker container can be used to
run the Web application on a local machine, making the interaction with the
application even faster.</p>
      <p>The paper is organised as follows. Section 2 details the o cial TED CAN
data, and how they were preprocessed for the OpenTED browser. Section 3
presents the OpenTED browser Web interface. Section 4 presents the lottery
game `Public spending is fun! who wants to be a supplier?', a `gami cation' of
the search for contract award notices. Section 5 concludes the paper with open
issues and perspectives.
2</p>
    </sec>
    <sec id="sec-2">
      <title>Data and Methods</title>
      <p>
        Raw data was retrieved from the Open Data portal of the European Union [
        <xref ref-type="bibr" rid="ref6">6</xref>
        ],
slightly preprocessed for easier querying, and converted to Parquet format for
e ciency reasons. We describe the data and preprocessing hereafter.
2.1
      </p>
      <sec id="sec-2-1">
        <title>Data overview</title>
        <p>
          The data comes from the European Economic Area, Switzerland, and the former
Yugoslav Republic of Macedonia and covers the time period between 2006/01/01
and 2015/12/31. It is in comma separated value (CSV) format and is encoded as
UTF-8. Generally, the data consists of notices above the procurement thresholds.
However, publishing below threshold notes in TED is considered good practice,
and thus a non-negligible number of below threshold notices is present as well
[
          <xref ref-type="bibr" rid="ref6">6</xref>
          ].
        </p>
        <p>2006 2007 2008 2009 2010 2011 2012 2013 2014 2015</p>
        <p>Year</p>
        <p>The number of countries covered has increased throughout the years,
generally in line with their accession to the single European market. This is illustrated
in Fig. 1, which reports the number of CANs per country and per year, since
s
e
c
i
to4e+05
n
d
r
a
w
a
t
c
a
tr
n
o
fc2e+05
o
r
e
b
m
u
N
0e+00
Contracting authority country</p>
        <p>France
Other
Poland
Germany
United Kingdom
Spain
Italy
Romania
Lithuania
2006. Only countries with more than 15,000 CANs per year are reported for
clarity reasons (number of CANs for other countries are summarized in `Other').</p>
        <p>The number of CANs increased from about 250,000 in 2006 to more than
500,000 in 2015, and a total of 4,283,986 CANs are available in the dataset. It is
worth noting that the number of CANs available per country is quite imbalanced,
and are the highest for France, Poland, Germany and the United Kingdom (UK).</p>
        <p>
          The data includes 48 selected elds from CANs (Table 3 in the Annex),
divided in six categories: Notice metadata, Contracting authority or entity identi
cation, Winning bidder identi cation, Various CAN level variables, and Various
CA level variables [
          <xref ref-type="bibr" rid="ref6">6</xref>
          ]. The size of the CSV le with all notices is slightly above
2GB.
2.2
        </p>
      </sec>
      <sec id="sec-2-2">
        <title>Data preparation and conversion to Parquet</title>
        <p>We remained as faithful as possible to the original data, and included all 4,283,986
records and 48 elds in the OpenTED browser. For making the ltering of the
dataset more user-friendly, we however renamed nine elds, which are highlighted
in the OpenTED browser (see Section 3). These elds consist in the date of the
CAN, the identi er (ID), the name and country of the contracting authority, the
name and country of the contractor, the value of the CAN, the number of o ers
and the CPV code. The renaming is detailed in Table 1.</p>
        <p>
          Besides the renaming, we also reformatted elds involving dates, countries,
and values. In the original data, date formats are Day-Months (3 rst
letters)Year (2 last digits), e.g., `31-DEC-13'. We reformatted it as Year (4
digits)Month (2 digits)-Day, e.g., `2013-12-31'. Such conversion makes it more suitable
to de ne ltering intervals on dates, using operator such as greater or less than
(e.g. date higher than `2013-06-01' and less than `2013-12-31' to get CANs from
the last six months of 2013). Country related elds were converted from the
ISO code (2 letters, e.g., `FR') to their full names (e.g., `France'). All award
value elds were converted from oats to integers. Finally, award notice IDs
were converted to hyperlinks linking to the CAN page on the o cial TED Web
site [
          <xref ref-type="bibr" rid="ref9">9</xref>
          ].
        </p>
        <p>
          Finally, we converted the CSV data to the Apache Parquet format [
          <xref ref-type="bibr" rid="ref15 ref2">2, 15</xref>
          ].
Apache Parquet is a columnar data storage format designed to support very
e cient compression and encoding schemes. Besides compression, Parquet also
allows data to be queried from the les using SQL like syntax, a feature which
we use in the browser. Data types were associated to CAN elds in order to
perform ltering and SQL queries, which we detail in Table 3. All elds related
to numbers were associated an Integer data type. Fields involving strings were
associated a String data type, or factor when the number of values was less than
300 hundreds. The use of the factor type allows to present users with a list of
choices in the TED browser ltering tool. After Parquet conversion, the dataset
size was reduced to 315MB.
        </p>
        <p>
          We make available the code for data preparation and Parquet conversion as
an IPython notebook [
          <xref ref-type="bibr" rid="ref13">13</xref>
          ].
3
        </p>
      </sec>
    </sec>
    <sec id="sec-3">
      <title>OpenTED browser</title>
      <p>
        The OpenTED browser is a Web application that provides a user-friendly
access to the CANs. Its main features are a ltering tool for extracting subsets of
CANs, and a visualisation tool that displays the relationships between
contracting authorities and contractors by means of a Sankey diagram. The OpenTED
browser is made available online at [
        <xref ref-type="bibr" rid="ref14">14</xref>
        ].
3.1
      </p>
      <sec id="sec-3-1">
        <title>Filtering tool</title>
        <p>The ltering tool allows to lter CANs by setting conditions on the content of
any of the CAN elds listed in Tables 1 and 3. A snapshot of the tool is given
in Fig. 2. All 48 elds can be ltered. The ltering operators provided for a eld
depends on the data type of the eld. A summary of available ltering operators
for a given data type is provided in Table 2.</p>
        <p>Conditions can be combined by logical conjunction and disjunction operators,
and may also be nested thanks to the grouping option. An example of ltering
is given in Fig. 2. The lter retrieves CANs for which: (i) the contracting
authority country is `Belgium', (ii) the CPV code either begins with `301' (O ce
machinery, equipment and supplies except computers, printers and furniture) or
`302' (Computer equipment and supplies) and (iii) the contract value in euros is
more than one million.</p>
        <p>
          Applying the lter returns the set of CANs matching the conditions. In the
example above, 128 CANs are returned, and displayed as a table below the
ltering widget. The table is interactive, and the user can reorder columns by
increasing or decreasing order of values. Award notice IDs are hyperlinks that
connect to the page of the CAN on the o cial TED Web site [
          <xref ref-type="bibr" rid="ref9">9</xref>
          ]. Finally, the set
of ltered CANs can be downloaded as a CSV using the `Download selection'
button.
3.2
        </p>
      </sec>
      <sec id="sec-3-2">
        <title>Sankey diagram</title>
        <p>Sankey diagrams visualise the magnitude of ow between nodes in a network.
They provide a useful visualisation tool for contract award notices, where
contracting authorities and contractors can be seen as nodes of a network, and the
contract values as ` ows'.</p>
        <p>
          The set of contracting authorities are represented on the left side of the
network, and the set of contractors on the right side. The thickness of the ow is
proportional to the sum of contract values between contracting authorities and
contractors.
The subjects of procurement contracts are encoded using Common Procurement
Vocabulary (CPV) [
          <xref ref-type="bibr" rid="ref10">10</xref>
          ]. CPV is based on a tree structure comprising codes of
up to 9 digits (an 8 digit code plus a check digit) associated with a wording
that describes the type of supplies, works or services forming the subject of
the contract. The rst two digits identify the general division, and subsequent
digits re ne the division into more speci c categories. For example, all codes
starting with 30 are from the general division of O ce and computing machinery,
equipment and supplies except furniture and software packages, while the code
3012453 refer more speci cally to Scanner transparency adapters.
        </p>
        <p>
          The meaning of CPV codes can be found from the EU Publications o ce [
          <xref ref-type="bibr" rid="ref10">10</xref>
          ].
In order to facilitate the use of CPV codes in the browser, we added a table with
all current CPV codes (9454 in total), that can be searched and ltered. The
table in available in the CPV codes tab, a snapshot of which is given in Fig. 4.
The user may x the number of digits in the results in order to restrict the search
to more general categories, and may sort the columns by increasing or decreasing
order of values. It should be noted that we only include the current nomenclature
(valid since 2008), and that the integration of the previous nomenclature (before
2008) is part of future work.
3.4
        </p>
      </sec>
      <sec id="sec-3-3">
        <title>Implementation</title>
        <p>
          The Web application was developed using R Shiny [
          <xref ref-type="bibr" rid="ref17">17</xref>
          ], and is made Open Source
at [
          <xref ref-type="bibr" rid="ref13">13</xref>
          ]. It is worth mentioning that thanks to the expressiveness of R Shiny, the
application is rather compact, i.e. less than 500 lines of code in total, making it
easily reusable and adaptable. We furthermore provide a Docker container for
facilitating its deployment on a di erent server, or run it on a local machine for
faster interaction with the browser [
          <xref ref-type="bibr" rid="ref14">14</xref>
          ].
4
        </p>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>Lottery game: Who wants to be a supplier?</title>
      <p>
        The lottery game is a third-party Web site aimed at promoting the OpenTED
browser [
        <xref ref-type="bibr" rid="ref12">12</xref>
        ]. The Web site gives the player a quest on tender data for nding
the biggest suppliers of some goods or services in a given country. Fig. 5 gives
a snapshot of the page, where the quest is to nd suppliers for `Insurance and
pension in Sweden in 2013'.
If the player accepts (\Let's play" button), she is redirected to the OpenTED
browser where the goal is to nd the subset of CAN corresponding to the quest.
She may also get the solution by selecting `Show me the solution', which will also
redirect to the OpenTED browser, but the ltering tool will be pre lled with
the set of conditions answering the quest. If the user does not like the quest, she
can ask for another one by selecting the `Not fun enough' button.
5
      </p>
    </sec>
    <sec id="sec-5">
      <title>Conclusion and perspectives</title>
      <p>The OpenTED browser provides an intuitive online gateway for ltering contract
award notices (CANs) of the European procurement system, and for getting
insights into the business relationships existing between contracting authorities
and entities. We believe that the tool, thanks to its simplicity and ease of use,
can be of signi cant interest for a number of users.</p>
      <p>Ongoing improvements concern the correction of inconsistencies in the data,
related to CPV codes and to the naming of contracting authorities and entities.
The nomenclature for CPV codes changed in 2008, which requires to adapt
queries to two nomenclatures when searching for CANs before and after 2008.
We plan to address this issue shortly. The second type of inconsistency relates to
variations in the naming of bidders and buyers. These may be caused by typos,
but are also due to di erent ways of naming an entity (e.g., Siemens, Siemens
A.G., Siemmens A.G., and so forth). While e orts to provide unique identi ers
instead of names are being promoted, name inconsistencies currently remain
an important challenge to properly group CANs according to their contracting
authorities and entities.</p>
      <p>In a larger perspective, a wide range of avenues exist for improving the
browsing of TED notices, and for providing better insights into tender data. To name
a few, possible extensions concern the integration of contract notices, also
recently made available by the Publications O ce as curated Open Data, and
make use of advanced analysis techniques such as clustering, graph analysis, or
outlier detection, to investigate questions such as what makes a bidder successful,
what are the tendering patterns among EU countries, or to identify indicators
of fraudulent behaviours.</p>
      <p>Acknowledgments. The authors acknowledge the support of \BruFence:
Scalable machine learning for automating defense system" (RBC/14 PFS-ICT 5), a
project funded by the Institute for the Encouragement of Scienti c Research
and Innovation of Brussels (INNOVIRIS, Brussels Region, Belgium),
Journalismfund.eu for organising the DataHarvest/European Investigative Journalism
Conference, the OpenTED working group (http://ted.openspending.org), the
European Union Publications O ce, http://ted.europa.eu, 1998{2016, and the
European Commision, Directorate-General for Internal Market, Industry,
Entrepreneurship and SMEs (DG-GROW) for providing the data, and Jachym
Hercher, Policy O cer at DG-GROW, for providing feedback and improvements
on this article.</p>
    </sec>
    <sec id="sec-6">
      <title>Appendix</title>
      <sec id="sec-6-1">
        <title>Integer Factor Factor String</title>
      </sec>
      <sec id="sec-6-2">
        <title>Unique identi er of the contract award notice String</title>
      </sec>
      <sec id="sec-6-3">
        <title>Year of publication of the notice Integer</title>
      </sec>
      <sec id="sec-6-4">
        <title>Standard form number Factor</title>
      </sec>
      <sec id="sec-6-5">
        <title>The date when the buyer dispatched (sent) the notice String for publication to TED</title>
      </sec>
      <sec id="sec-6-6">
        <title>Version of the XML schema de nition [ADDED] Factor 1 = this notice was later cancelled [ADDED] Factor</title>
      </sec>
      <sec id="sec-6-7">
        <title>O cial name</title>
        <p>\National ID" e.g. VAT number for utilities</p>
      </sec>
      <sec id="sec-6-8">
        <title>Postal address</title>
      </sec>
      <sec id="sec-6-9">
        <title>Town</title>
      </sec>
      <sec id="sec-6-10">
        <title>Postal code</title>
      </sec>
      <sec id="sec-6-11">
        <title>Country O cial name Postal address Town</title>
      </sec>
    </sec>
  </body>
  <back>
    <ref-list>
      <ref id="ref1">
        <mixed-citation>
          1.
          <string-name>
            <surname>Alvarez</surname>
            ,
            <given-names>J.M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Labra</surname>
            ,
            <given-names>J.E.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Cifuentes</surname>
            ,
            <given-names>F.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Alor-Hernandez</surname>
            ,
            <given-names>G.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Sanchez</surname>
            ,
            <given-names>C.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Luna</surname>
            ,
            <given-names>J.A.G.</given-names>
          </string-name>
          :
          <article-title>Towards a pan-european e-procurement platform to aggregate, publish and search public procurement notices powered by linked open data: the moldeas approach</article-title>
          .
          <source>International Journal of Software Engineering and Knowledge Engineering</source>
          <volume>22</volume>
          (
          <issue>03</issue>
          ),
          <volume>365</volume>
          {
          <fpage>383</fpage>
          (
          <year>2012</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref2">
        <mixed-citation>
          2. Apache Software Foundation: Parquet, https://parquet.apache.org/,
          <source>(Viewed June</source>
          <year>2016</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref3">
        <mixed-citation>
          3.
          <string-name>
            <surname>Cernat</surname>
            ,
            <given-names>L.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Kutlina-Dimitrova</surname>
            ,
            <given-names>Z.</given-names>
          </string-name>
          :
          <article-title>International public procurement: From scant facts to hard data. Robert Schuman Centre for Advanced Studies Research Paper No</article-title>
          .
          <source>RSCAS</source>
          (
          <year>2015</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref4">
        <mixed-citation>
          4.
          <string-name>
            <surname>De La Iglesia</surname>
            ,
            <given-names>J.L.M.:</given-names>
          </string-name>
          <article-title>Alternative estimation of public procurement advertised in the o cial journal as of GDP o cial indicator using open government data</article-title>
          .
          <source>Computers in Industry</source>
          <volume>65</volume>
          (
          <issue>5</issue>
          ),
          <volume>905</volume>
          {
          <fpage>912</fpage>
          (
          <year>2014</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref5">
        <mixed-citation>
          5.
          <string-name>
            <given-names>DG</given-names>
            <surname>GROW G4 - Innovative and</surname>
          </string-name>
          e-Procurement:
          <article-title>2014 public procurement indicators</article-title>
          .
          <source>(February</source>
          <year>2016</year>
          ), http://ec.europa.eu/DocsRoom/documents/15421/
        </mixed-citation>
      </ref>
      <ref id="ref6">
        <mixed-citation>
          6.
          <string-name>
            <given-names>DG</given-names>
            <surname>Internal</surname>
          </string-name>
          <string-name>
            <surname>Market</surname>
          </string-name>
          , Industry, Entrepreneurship, and SMEs, European Commission, Brussels: Ted csv dataset (2006
          <article-title>-2015), tenders electronic daily, supplement to the o cial journal of the european union</article-title>
          , https://open-data.europa.eu/cs/ data/dataset/ted-csv,
          <source>version 2</source>
          .0. Accessed on 2016-
          <volume>06</volume>
          -25.
        </mixed-citation>
      </ref>
      <ref id="ref7">
        <mixed-citation>
          7. DIGIWHIST - Deliverable 1.
          <fpage>1</fpage>
          .:
          <article-title>Towards a comprehensive mapping of information on public procurement tendering and its actors across europe</article-title>
          .
          <source>(August</source>
          <year>2015</year>
          ), http://digiwhist.eu/wp-content/uploads/2016/01/DIGIWHIST_D1_
          <fpage>1</fpage>
          -
          <lpage>AccessToTenderInfo</lpage>
          .pdf
        </mixed-citation>
      </ref>
      <ref id="ref8">
        <mixed-citation>
          8.
          <string-name>
            <given-names>European</given-names>
            <surname>Commission</surname>
          </string-name>
          :
          <article-title>The publications o ce of the european union (</article-title>
          <year>2016</year>
          ), http: //publications.europa.eu,
          <source>(Viewed June</source>
          <year>2016</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref9">
        <mixed-citation>
          9.
          <string-name>
            <surname>European</surname>
          </string-name>
          <article-title>Commission: TED. tenders electronic daily (</article-title>
          <year>2016</year>
          ), http://ted.europa. eu,
          <source>(Viewed June</source>
          <year>2016</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref10">
        <mixed-citation>
          10.
          <string-name>
            <surname>European Union Publications O ce: Common Procurement Vocabulary</surname>
          </string-name>
          (
          <year>2008</year>
          ), uRL: https://simap.ted.europa.eu/cpv. Viewed June 2016.
        </mixed-citation>
      </ref>
      <ref id="ref11">
        <mixed-citation>
          11.
          <string-name>
            <surname>Hoekman</surname>
            ,
            <given-names>B.</given-names>
          </string-name>
          :
          <article-title>International cooperation on public procurement regulation</article-title>
          .
          <source>Robert Schuman Centre for Advanced Studies Research Paper No. RSCAS</source>
          <volume>88</volume>
          (
          <year>2015</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref12">
        <mixed-citation>
          12.
          <string-name>
            <surname>Homolova</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          :
          <article-title>Lottery game: Who wants to be a supplier</article-title>
          . (
          <year>2015</year>
          ), uRL: http: //supplier.tenders.exposed/.
          <source>Viewed June</source>
          <year>2016</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref13">
        <mixed-citation>
          13.
          <string-name>
            <surname>Le Borgne</surname>
            ,
            <given-names>Y.A.</given-names>
          </string-name>
          :
          <article-title>IPython notebook for data preparation and Parquet conversion (</article-title>
          <year>2016</year>
          ), https://github.com/Yannael/OpenTED, viewed
          <year>June 2016</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref14">
        <mixed-citation>
          14.
          <string-name>
            <surname>Le Borgne</surname>
            ,
            <given-names>Y.A.</given-names>
          </string-name>
          :
          <article-title>Opented browser web site (</article-title>
          <year>2016</year>
          ), http://yleborgne.net/ opented, viewed
          <year>June 2016</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref15">
        <mixed-citation>
          15.
          <string-name>
            <surname>Melnik</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Gubarev</surname>
            ,
            <given-names>A.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Long</surname>
            ,
            <given-names>J.J.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Romer</surname>
            ,
            <given-names>G.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Shivakumar</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Tolton</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Vassilakis</surname>
            ,
            <given-names>T.</given-names>
          </string-name>
          :
          <article-title>Dremel: Interactive analysis of web-scale datasets</article-title>
          .
          <source>In: Proc. of the 36th Int'l Conf on Very Large Data Bases</source>
          . pp.
          <volume>330</volume>
          {
          <issue>339</issue>
          (
          <year>2010</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref16">
        <mixed-citation>
          16.
          <string-name>
            <surname>Miroslav</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Milos</surname>
            ,
            <given-names>M.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Velimir</surname>
            ,
            <given-names>S.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Bozo</surname>
            ,
            <given-names>D.</given-names>
          </string-name>
          ,
          <string-name>
            <surname>Jorje</surname>
            ,
            <given-names>L.</given-names>
          </string-name>
          :
          <article-title>Semantic technologies on the mission: Preventing corruption in public procurement</article-title>
          .
          <source>Computers in Industry</source>
          <volume>65</volume>
          (
          <issue>5</issue>
          ),
          <volume>878</volume>
          {
          <fpage>890</fpage>
          (
          <year>2014</year>
          )
        </mixed-citation>
      </ref>
      <ref id="ref17">
        <mixed-citation>
          17. RStudio, Inc: Easy web applications in R. (
          <year>2013</year>
          ), uRL: http://www.rstudio.com/ shiny/.
          <source>Viewed June</source>
          <year>2016</year>
          .
        </mixed-citation>
      </ref>
      <ref id="ref18">
        <mixed-citation>
          18.
          <string-name>
            <surname>Uyarra</surname>
          </string-name>
          , E.:
          <article-title>Review of measures in support of public procurement of innovation</article-title>
          .
          <source>Report within the MIoIR-NESTA Compendium of Evidence on Innovation Policy. London/Manchester</source>
          (
          <year>2013</year>
          )
        </mixed-citation>
      </ref>
    </ref-list>
  </back>
</article>