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<article xmlns:xlink="http://www.w3.org/1999/xlink">
  <front>
    <journal-meta>
      <journal-title-group>
        <journal-title>Computational Humanities Research Conference, November</journal-title>
      </journal-title-group>
    </journal-meta>
    <article-meta>
      <title-group>
        <article-title>Event Flow - How Events Shaped the Flow of the News, 1950-1995</article-title>
      </title-group>
      <contrib-group>
        <contrib contrib-type="author">
          <string-name>Melvin Wevers</string-name>
          <xref ref-type="aff" rid="aff1">1</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Jan Kostkan</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Kristofer L.</string-name>
        </contrib>
        <contrib contrib-type="author">
          <string-name>Nielbo</string-name>
          <xref ref-type="aff" rid="aff0">0</xref>
        </contrib>
        <aff id="aff0">
          <label>0</label>
          <institution>Center for Humanities Computing Aarhus, Aarhus University</institution>
          ,
          <country country="DK">Denmark</country>
        </aff>
        <aff id="aff1">
          <label>1</label>
          <institution>Department of History, University of Amsterdam</institution>
          ,
          <addr-line>Amsterdam</addr-line>
          ,
          <country country="NL">the Netherlands</country>
        </aff>
      </contrib-group>
      <pub-date>
        <year>2021</year>
      </pub-date>
      <volume>1</volume>
      <issue>4</issue>
      <fpage>7</fpage>
      <lpage>19</lpage>
      <abstract>
        <p>This article relies on information-theoretic measures to examine how events impacted the news for the period 1950-1995. Moreover, we present a method for event characterization in (unstructured) textual sources, ofering a taxonomy of events based on the diferent ways they impacted the flow of news information. The results give us a better understanding of the relationship between events and their impact on news sources with varying ideological backgrounds.</p>
      </abstract>
      <kwd-group>
        <kwd>eol&gt;computational history</kwd>
        <kwd>historical newspapers</kwd>
        <kwd>information theory</kwd>
        <kwd>event characterization</kwd>
      </kwd-group>
    </article-meta>
  </front>
  <body>
    <sec id="sec-1">
      <title>1. Introduction</title>
      <p>
        Huddled around television sets or with ears clung to radio receivers, people all around the
world heard Neil Armstrong utter the words: “[t]hat’s one small step for man; one giant leap
for mankind.” This landmark event took place on July 21, 1969. The date denotes the day on
which the landing took people, even though one could convincingly argue that this day is part
of a sequence of events leading up to this historic moment. In the days before the landing,
newspapers published articles that counted down to the event and added commentary to the
event, fueling anticipation in public discourse. On a longer time scale, the moon landing was
part of a larger event: the space race, a competition between the United States and the Soviet
Union for technological dominance. This distinction calls to mind Fernand Braudel’s famous
description of events as “surface disturbances, crests of foam that the tides of history carry on
their strong backs [
        <xref ref-type="bibr" rid="ref3">3</xref>
        ].”
      </p>
      <p>
        Events, such as the moon landing, are essential for our experience of history. We do not
perceive time as is but through our experience of change in which events demarcate historical
temporality. We rely on events to structure the world around us, as individuals and as
societies [
        <xref ref-type="bibr" rid="ref25">25</xref>
        ]. William H. Sewell, Jr. describes an event as “an occurrence that is remarkable in
some way - one that is widely noted and commented on by contemporaries [
        <xref ref-type="bibr" rid="ref23">23</xref>
        ].” In the book
What is an Event?, Wagner-Pacifici uses 9/11 as a key example to theorize about the form
and flow of events. She points out that historians have been preoccupied with bounding events
in time and space, while she emphasizes “the ongoingness of events.” As an event unfolds, it
disrupts the historical flow while the public tries to make sense of what is happening.
Afterward, the public reflects on these events and sets out to integrate these events into a historical
narrative. As events gain traction, they transform how we experience historical time.
      </p>
      <p>
        Understanding how historical temporality difers from natural temporality is crucial for
“understanding how history has shaped the identity of modern society and culture.[
        <xref ref-type="bibr" rid="ref13">13</xref>
        ]” History
is a process of both remembering and forgetting events and their relations. For contemporary,
the moon landing was a singular event unlike any other, yet, canonized history knows more
than one of these singular events. Was the moon really as impactful at the time, or has the
wheel of time strengthen its position in our collective memories.
      </p>
      <p>As Wagner-Pacifici points out, events cannot always be tied to exact dates, even though
historical events are often connected to specific dates, such as the moon landing, the fall of
the Berlin Wall, or winning a European soccer final. Rather than only departing from specific
dates in a top-down manner, can we also detect the unfolding of events and their impact on
the historical flow in a more data-driven, bottom-up manner? This paper sets out to answer
this question by analyzing the relationship between events and the historical flow, represented
by the information presented on the front pages of newspapers.</p>
      <p>In our case, we model the ways events impacted language use. More specifically, we examine
disruptions in the information flow of news on front pages. For example, events can disrupt
the flow of the news by decreasing the amount of novel information presented on the front
pages. In the run-up to an event, an increasing focus of the public’s eye might be reflected
in the increasing uniformity of discourse. Alternatively, an event could have a sudden impact
while retaining the public’s attention for an extended period. One could hypothesize diferent
archetypical forms of events. In what follows, we try to establish universal motifs, or event
lfows, from the data itself. The three central questions to this paper are: (1) Do events impact
historical flow, as represented by front pages in newspapers? (2) Can we cluster events based
on the way they impacted the flow of information? (3) Can we use these clusters to query for
events? We call these clusters, event flows, as they represent generalized manners in which
events have impacted historical flow. 1</p>
      <p>
        A recent special forum in the journal History and Theory clearly describes the long-standing
historiographical debate on the concept of the event [
        <xref ref-type="bibr" rid="ref11">11</xref>
        ]. One of the main challenges in history
is to combine theoretical work on events with empirical studies of the temporality of events
and their relationship to collective memory. The authors claim that systemic analysis of the
temporal nature of events, which could shed light on an event’s identity, are largely unexplored.
This paper ofers a computational method that contributes to this efort to understand better
how events and their temporal structure have afected public discourse and, by extension,
collective memory.
      </p>
    </sec>
    <sec id="sec-2">
      <title>2. Related Work</title>
      <p>
        Previous studies have shown that word usage in newspapers is sensitive to the dynamics of
socio-cultural events [
        <xref ref-type="bibr" rid="ref5 ref7 ref9">9, 7, 5</xref>
        ]. Furthermore, the co-occurrence of words in newspaper reporting
has been shown to capture thematic development accurately [
        <xref ref-type="bibr" rid="ref16">16</xref>
        ], and, when modeled
dynam1Data and code supporting this paper have been made available at https://doi.org/10.5281/zenodo.5509949
(data) and https://github.com/melvinwevers/event-flow (code).
ically, is indicative of the evolution of cultural values and biases [
        <xref ref-type="bibr" rid="ref20 ref26 ref7">7, 20, 26</xref>
        ]. Methods from
complexity science, such as Adaptive Fractal Analysis, have been used to identify distinct
domains of newspaper content based on temporal patterns in word use (e.g., advertisements and
articles) [27] and to discriminate between diferent classes of catastrophic events that display
class-specific fractal signatures in, among other things, word usage in newspapers [
        <xref ref-type="bibr" rid="ref8">8</xref>
        ].
      </p>
      <p>
        Several studies have shown that measures of (relative) entropy can detect fundamental
conceptual diferences between distinct periods [
        <xref ref-type="bibr" rid="ref12 ref6 ref9">9, 6, 12</xref>
        ], concurrent ideological movements (e.g.
progressive and conservative politics) [
        <xref ref-type="bibr" rid="ref1 ref2">1, 2</xref>
        ], and even, the development of ideational factors
(e.g., creative expression) in writing with a serial structure [
        <xref ref-type="bibr" rid="ref15">15, 19, 18</xref>
        ]. More specifically, a
set of methodologically related studies have applied windowed relative entropy to thematic
text representations to generate signals that capture information novelty as a reliable content
diference from the past and resonance as the degree to which future information conforms to
said novelty [
        <xref ref-type="bibr" rid="ref1 ref15">1, 15</xref>
        ]. Two recent studies have found that successful social media content shows
a strong association between novelty and resonance [
        <xref ref-type="bibr" rid="ref17">17</xref>
        ], and that variation in the
noveltyresonance association can predict significant change points in historical data [
        <xref ref-type="bibr" rid="ref24">24</xref>
        ].
      </p>
      <p>
        Our paper builds upon this work and will adapt the windowed relative entropy approach
to a method that we call Jump Entropy. This method allows us to examine how events have
impacted the flow of information in and between newspapers. We compare time series between
newspapers and events, using Dynamic Time Warping Barycenter Averaging (DBA) [
        <xref ref-type="bibr" rid="ref21">21</xref>
        ].
      </p>
    </sec>
    <sec id="sec-3">
      <title>3. Data</title>
      <p>Front pages function as the pulse of the nation, displaying current and pressing events at
specific time points. Figure 1, for example, depicts the front page in Algemeen Handelsblad
published on the day after the moon landing, which took place on a Sunday. In big, bold
letters, we read: “Walking on the Moon.”2 Multiple articles on this event feature on this front
page. In addition to the text, we see three images documenting this historic moment. For
this study, we only looked into the textual content—captured by optical character recognition
(OCR)—and not at the images. The data consists of the textual content represented on the
front pages of ten Dutch national and regional newspapers published between 1950 and 1995
(See Table 1 for details).3</p>
      <p>For the data processing, which is not perfect due to flaws in the OCR technology, we removed
stop words, punctuation, digits, and words shorter than three and longer than seventeen
characters. We lemmatized the text using the NLP toolkit SpaCy.4 Next, we used Latent Dirichlet
Allocation (LDA) with collapsed Gibbs sampling to train a topic model of the data.5 The
input document for topic modeling consisted of a concatenation of all the articles on one
single front page. This yields a matrix per newspaper of P (topick|documentd) or θ, in this case
documentd refers to a front page on a specific date and topick holds the probability distribution
of topics over documents. These ten matrices functioned as input for the calculation of the
Jump Entropy.</p>
      <p>2Translated from the Dutch phrase “Wandelen op de maan”.
3It is important to note that not all newspapers run for the entire period.
4https://spacy.io/
5Using topic coherence, the optimal number of topics (k) centered on 100. Going above or slightly below
this number did not impact the results. However, when too few topics are selected the matrix becomes too
sparse which makes it difficult to detect shifts in entropy.</p>
      <p>In addition to the newspaper data, we constructed a list of sixty events for 1950-1995, using
historical subject-matter knowledge combined with Wikipedia.6 This list includes global and
national events.</p>
      <sec id="sec-3-1">
        <title>6See Appendix A for an overview of these events.</title>
      </sec>
    </sec>
    <sec id="sec-4">
      <title>Method</title>
      <p>
        Jump Entropy To measure the flow of information between front pages, we propose an
adapted version of the approach introduced by [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ]. Barron et al. [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ] measured the amount
of novelty (how unexpected is a document, given previous documents) and transience (the
degree to which patterns in documents fade or persist in future documents). They calculate
this using varying window sizes, i.e. comparing the novelty of document compared to the
average relative entropy contained in a varying number of documents. Relative entropy is a
divergence measure that is able to capture the amount of “surprise” between two probability
distributions, where (in this case) the reader learns to expect one distribution, ⃗p, and then
encounters second, say ⃗q. These probability distributions are captured in θ, i.e. the topic
distributions from one time point compared to another. In our case, this would be between
front pages in one newspaper.
      </p>
      <p>Calculating novelty and transience using this windowed approach assumes that information
accumulates in a continuous flow. This approach is quite sensitive to outliers, especially for
shorter time windows. Also, due to the cyclical nature of events (e.g. seasonal or annual
events), or the cascading, ripple efect in which an event might have impacted newspaper
discourse, taking a continuous window might flatten out these efects.</p>
      <p>To better capture the efect of an event on diferent time scales and trace ripple efects in
public discourse, we adapted their approach. We introduce Jump Entropy, an approach that
replaces the shifting window for jumps of diferent sizes. Rather than moving through the set
linearly, we compare sets of front pages that are separated by a given distance. This distance
between the two sets is expressed by J , the jump size. While using a fixed range of documents
(14 days, t - 7 and t + 7), we vary the jump size (J ) and calculate the JSD between a set of
front pages around the focal point t and front pages around a focal point either in the past
(negative jump size) or the future (positive jump size).7</p>
      <p>
        While [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ] compare one front page with a range of front pages, this method compares two
ranges of front pages separated by a jump. Put diferently, we measure the average entropy
for a range of documents and then jump into the past or future and compare this range to
a similar range in this period. This approach allows us to measure the amount of “surprise”
between the focal set to a set in the past or the future; as such, we can spot re-use of themes
      </p>
      <sec id="sec-4-1">
        <title>7We also experimented with shorter time windows, but this adds noise to the signal.</title>
        <p>or recurring debates. Compared to the windowed approach, this method is less sensitive to
outliers. We can find cyclical patterns, i.e., which period in the past or future is most similar
to the focal period.</p>
        <p>
          In addition to adding jumps, we also used a diferent metric than [
          <xref ref-type="bibr" rid="ref1">1</xref>
          ]. Rather than using
Kullback-Leibler (KLD), we used Jensen-Shannon divergence (JSD), a less well-known
formulation of relative entropy. JSD has several favorable properties when dealing with cultural
information that is not produced in a strictly one-directional fashion. While newspapers are
published day by day, the information represented in the papers is not necessarily produced
in a one-directional fashion. Articles might have been written earlier, or authors might reflect
back onto earlier events. We contend that JSD better reflects these assumptions. First and
foremost, JSD is symmetric ensuring that J SD(P |Q) = J SD(Q|P ) for probability
distributions P and Q. Second, as a smooth version of KLD, JSD is well-behaved when P and Q are
small. Finally, the square root of JSD is a proper distance metric that can be, for example, be
used for clustering probability distributions. A disadvantage of JSD compared to KLD is that
it is more computationally costly. However, this additional cost does not significantly impact
the current study.
        </p>
        <p>We model the diference between articles s(j) and s(k) as their relative entropy:
J SD(s(j) | s(k)) = 1 D(s(j) | M ) + 1 D(s(k) | M )</p>
        <p>2 2
with M = 12 (s(j) + s(k)) and D is the Kullback-Leibler divergence:</p>
        <p>K s(j)
D(s(j) | s(k)) = ∑ s(j) × log2 s(k)</p>
        <p>i
i
i=1 i</p>
        <p>We calculated the average relative entropy between a range (t) of topic distributions (s) at
moment i (si+t) and the same range of documents at moment j (sj+t). t ranged from -14 to
14, and the jump size (J ) ranges between -1500 and 1500 with steps of 15:</p>
        <p>JJ (i) =</p>
        <p>j=1
w1 ∑w D(s(i) | s(i+vj)), v = {1−,1, iofthtjer&lt;wi0se , for all J s
Where D is the distance measure (in this case J SD), w is a window size and J is the set of
jumps of size w, and t is the time point (‘direction’) at which JJ (i) is computed.</p>
        <p>After calculating the jump entropies for a newspaper, we can use them to visualize event
lfows. Figure 2 shows the event flow for eight random event in the newspaper De Volkskrant.
For each figure, on the x-axis, we see the jump size, and on the y-axis, the relative entropy.
The center of the x-axis (0) indicates the date of the event, and to the left we see jumps in
the past and to the right jumps into the future. This graph captures the flow of information
leading up to and after the event.</p>
        <p>
          Comparing Event Flows To group events within and between newspapers in an unsupervised
manner requires a method to cluster dynamic processes and compute archetypical (averaged)
representations of these time series. Dynamic-Time Warping Barycenter Averaging (DBA)
is an ideal solution for exactly that. DBA is based on Dynamic Time Warping (DTW), a
technique for optimally aligning time series and flexibly capturing similarities inside the series
[
          <xref ref-type="bibr" rid="ref21">21</xref>
          ]. As such, DTW accounts for non-linear variations in the time series, i.e., fluctuations do
(1)
(2)
(3)
not need to occur at the same time steps [
          <xref ref-type="bibr" rid="ref22">22</xref>
          ]. In some data sets, it has been shown that
Euclidean distance is outperformed by DTW, which has invariance to local misalignments in
time [
          <xref ref-type="bibr" rid="ref14 ref21">14, 21</xref>
          ].
        </p>
        <p>
          In principle, DTW allows us to align and compare events between newspapers. However,
as pointed out by [
          <xref ref-type="bibr" rid="ref21">21</xref>
          ], while DTW is one of the most used similarity measures for time
series, it cannot be reliably used for clustering using well-known algorithms since they rely
on K-medoids, which require no averaging. DBA ofers an extension of DTW to compute a
consensus representation for a set of time series [
          <xref ref-type="bibr" rid="ref21">21</xref>
          ]. This allows us to calculate the average
event flow for one event using data from ten newspapers. Figure 3 gives an example of this
process using a DBA and a smoothened version of DTW (soft-DTW) using a soft minimum.
Petitjean, Ketterlin, and Gançarski show that DBA can be used as input for the k-means
clustering of time series.
        </p>
        <p>Rather than using k-means clustering, we applied agglomerative clustering. This approach
has two main advantages over k-means clustering. First, the method is more explainable;
we can inspect how clusters are created, how they are distributed over the dataset, and which
clusters are more similar than others. Second, agglomerative clustering led to better separation
of the clusters than k-means clustering (see Figure 4).</p>
        <p>We clustered using the following steps:
1. Applying a window size of 28.8
2. Time series were z-normalized.
3. Calculate pairwise DTW distance between the events, acquiring a distance matrix.
8There were four to five clusters for all window sizes between five and fifty. We settled for 28 days for
interpretative reasons, as it corresponds to four weeks, or approximately a month of front pages.</p>
        <p>4. Project the distance matrix in to two dimensions using UMAP (Uniform Manifold
Approximation and Projection).
5. Grid search through clustering parameters (number of clusters, clustering method),
aiming for a high Silhouette score. Additional sanity checks of cluster coherence were taken
using the UMAP projection.
6. After the grid search, euclidean distance was picked as the clustering metric, while
UPGMA (unweighted pair group method with arithmetic mean), also known as average
linkage, was picked as the linkage criterion.</p>
        <p>7. Calculate an archetypical time series using DBA for each found cluster.</p>
        <p>Using the described methods, we executed the following steps:
• compare similarities and diferences between events across newspapers
• establish archetypical event flows using agglomerative clustering
• use an averaged event flow to query for similar events</p>
      </sec>
    </sec>
    <sec id="sec-5">
      <title>4. Results</title>
      <p>In what follows, we will first check whether there exists a diference between newspapers and
specific event flows. This step helps us establish for which events there was consensus among
newspapers or which newspapers deviated in their reporting on a particular event. Rather
than just focusing on our selection of events, we also use a list of random dates as a baseline.
(a) K-means clustering
(b) Agglomerative clustering
Newspaper diference using random dates We selected the event flows with a jump size of
thirty, i.e, thirty days in the future and thirty in the past, for 1,000 random dates between 1950
and 1995 from all the included newspapers. After z-normalizing the time series for every date,
we calculated the average event flow per date using DBA. Next, we calculated the distance
for each newspaper to each date’s average event flow using DTW. This distance to the mean
shows us which newspapers deviated the most from the average for that date. In Figure 5, we
see the distance from the mean per newspaper grouped per decade.</p>
      <p>
        From Figure 5, we can gauge that the regional newspaper Leeuwarder Courant (LC) and
national newspaper De Telegraaf deviated the most from the mean, with the latter diverging
considerably over the course of these fifty years. This confirms what we knew about the
country’s most popular newspaper’s ideological course, which moved to the right in this period [
        <xref ref-type="bibr" rid="ref10">10</xref>
        ].
Also, the changing course of the Leeuwarder Courant dovetails with the merger of the
newspaper with another regional newspaper Friese Koerier [
        <xref ref-type="bibr" rid="ref4">4</xref>
        ]. It might be that this merger has
pushed the newspaper toward to average Dutch newspaper landscape.
      </p>
      <p>Newspaper diferences using selected events In addition to calculating the diference
between papers for random dates, we used our list of events. For each event, we calculated an
average event flow using DBA. Next, we calculated the distance from each event per newspaper
to the average event flow. From this, we learn for which events the event flows in newspapers
were the most similar, and for which events newspapers diverged.9</p>
      <p>Figure 6 shows that the top five events on which the newspapers reported uniformly were:
the Suez crisis in 1956, the 1973 oil crisis, the Nigerian civil war (1967-1970), the fall of Saigon
(April 30, 1975), and the moon landing (July 21, 1969). We also see that NRC Handelsblad,
Het Parool, Het Vrije Volk, and De Volkskrant, were most closely aligned in terms of their
event flows, with De Telegraaf and Leeuwarder Courant, again, being the outliers. Here we
9Since Algemeen Handelsblad and De Tijd only appeared for a small subset of the period, we excluded these
two newspapers
also clearly see how De Telegraaf is behaving quite distinct compared to the other newspapers.
Especially on Middle Eastern afairs, such as the Yom Kippur War (1973) and the Iran hostage
crisis (1979-1981), other papers were very much in line with De Telegraaf being the exception.
Archetypical time series Using DBA in combination with agglomerative clustering, we looked
for clusters of event flows in our data. We excluded De Telegraaf because of its deviant
behavior. Using a window size of 28, we used the 58 events for the nine remaining newspapers as
input. Using Silhouette analysis and cluster separation in the UMAP projection, we determined
that the optimal number of clusters was closest to five. Figure 7 shows the average event flows
within these five clusters.</p>
      <p>From this clustering, we learn that events impacted the news in five characteristic manner.</p>
      <p>These manner capture how this impact unfolded over time and helps us to understand how
events impacted the flow of information in the news, and by extension, how events impacted
our historical temporality. The five clusters can be described as follows:
• Cluster 1: The downward slope before the event indicates a growing focus on an event,
with a slow release indicating persisting, albeit abating focus on the topic after the event.
• Cluster 2: The downward slope before the event indicates a growing focus on an event,
with a flat line after the event indicative of a persistent focus on a topic after the event.
Compared to Cluster 1, the event’s impact is more sudden, and it captured the public’s
attention for a longer period.
• Cluster 3: A noisy pattern that indicates no clear anticipation and a quick release after
the event. Events with this signature might have occurred in periods with a quick news
cycle, i.e., many news events rapidly superseding each other.
• Cluster 4: Stable entropy, indicated by lack of slope, which suggests an increasing focus
on a topic in the days before an event. The slope after the event indicates a release of
focus after the event. This cluster is the mirror version of Cluster 2 and, to a lesser
extent, Cluster 1.
• Cluster 5: This cluster is most similar to cluster 4, albeit more balanced. There is
growing anticipation and a release after the event. These event characteristics are
indicative of events, such as the Moon Landing, that capture the public’s attention in the
days before and after an event.</p>
      <p>Querying for Events One of the applications of the cluster-based approach is that we can use
the average event flow of a cluster (indicated by bold lines), to query for front pages that exhibit
a similar pattern. This allows us to search for all the front pages in a particular newspaper
that exhibit a sudden focus on a topic, as expressed by Cluster 5. Alternatively, we could also
take a specific event, for example, the Oil Crisis in the 1970s, and look for similar events.</p>
    </sec>
    <sec id="sec-6">
      <title>5. Conclusion</title>
      <p>
        We have presented an adaptation to the method introduced in [
        <xref ref-type="bibr" rid="ref1">1</xref>
        ], which allows us to capture
how events impacted newspaper discourse, and by extension, reveal how the public’s eye was
drawn to specific events. We have shown how this method can be used to compare how
newspapers responded to events and characterize events based on their impact on newspaper
discourse.
      </p>
      <p>The interaction between newspapers and the outside world is a complex interaction.
Nonetheless, we managed to characterize ways in which front pages responded to world events. We
can use these characterizations to define archetypical time series that can be used to query
newspaper data to locate similar events. In this study, we have shown that there were events
that impacted the news even though they are not remembered as having an impact, or vice
versa. In future work, we will examine how these disjunctions between the public’s memory of
events and their impact on the news related to the canonization of historical events.</p>
      <p>Also, we found that some noteworthy events displayed no clear signal (cluster 3). For
example, the accident with the Challenger space shuttle on January 28, 1986, or the Coup in
Ethiopia on December 13, 1960, did not elicit a clear response in the newspapers. For now, we
can only speculate about the reasons that these events did not impact the information flow on
the front pages of Dutch newspapers. One possibility is that the events did not grasp public
attention. Alternatively, it could be that the event was discussed in a more specialized section
or that the general public only identified an event as newsworthy well after it occurred.</p>
      <p>Closer examination shows that the earthquakes in Chili in May 1960 followed the event flow
displayed in Cluster 1, which might seem surprising. However, in this case, there was also a
summit with world leaders taking place that increasingly captured the public’s attention. The
earthquake disrupted this trend and suddenly introduced a new topic, herewith increasing the
entropy. This example also highlights one of the shortcomings of this approach. Events can
overlap each other, move away from the front pages, and after a turn of events they might
return to the front again. This movement throughout the papers is not yet captured with
this approach. Future work will examine the relationships between topics on the front pages
and how they propagated throughout the newspaper. Retention, for instance, could also be
expressed by more in-depth reflections on the events in dedicated newspaper sections.</p>
    </sec>
    <sec id="sec-7">
      <title>Acknowledgments</title>
      <p>This study was a NeiC’s Nordic Digital Humanities Laboratory project (DeiC-AU1-L-000001),
executed on the DeiC Type-1 HPC cluster. We acknowledge The National Library of the
Netherlands (KB) for making their newspaper data available. Also, we express our gratitude
to Simon DeDeo for his input during the early stages of this paper. Finally, we thank Eamonn
Keogh for his comments on an earlier version.
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date
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