2019-03-05: 365 dots in 2018 - top news stories of 2018

Fig. 1: News stories for 365 days in 2018. Each dot represents the average degree of the Giant Connected Component (GCC) with the largest average degree across all the 144 story graphs for a given day. The x-axis represents time, the y-axis represent the average degree of the selected GCC. Click to expand image.

There was no shortage of big news headlines in 2018. Amidst this abundance, a natural question is what were the top news stories of 2018? There are multiple lists from different news organizations that present candidate top stories in 2018 such as CNN's most popular stories and videos of 2018, and The year in review: Top news stories of 2018 month by month from CBS. Even though such lists from respectable news organizations pass the "seems right test," they mostly present the top news stories without presenting an explanation for their process. In other words, they often do not state why some story made the list and why another did not make the list. We consider such information very helpful for two reasons. First, an explanation or presentation of the criteria of why some story made the list opens the criteria to critique and helps alleviate concerns about bias. Second, the criteria is inherently valuable because it could be reused and reapplied on a different collection. For example, one could apply the process to find out the top news stories in a different country.

Fortunately, StoryGraph is well suited to answer our main question, "what were the top news stories of 2018?"

A brief introduction of StoryGraph
We plan to publish a blogpost introducing and explaining StoryGraph in the near future. However, here is a quick explanation. StoryGraph is a service that periodically (10-minute intervals) generates a news similarity graph. In this graph, the nodes represent news stories and an edge between a pair of nodes represents a high degree of similarity between the nodes (news stories). For example, this story, In eulogy, Obama says McCain called on nation to be ‘bigger’ than politics ‘born in fear’ is highly similar (similarity: 0.46) to this story, John McCain honored at National Cathedral memorial service, therefore an edge exists between both stories in their parent story graph.
Small stories vs big stories: how StoryGraph quantifies the magnitude of news stories
On a slow news day, news organization report on multiple different news stories. This results in a low degree of similarity between pairs of news stories (e.g., Fig. 2) and results in smaller connected components.
In contrast, shortly after a major news event, news organizations publish multiple highly similar news stories. This results in a high degree of similarity between pairs of news stories. This often leads to a Giant Connected Component (GCC) in the news story graph  (e.g., Fig. 3).
Fig. 2: A small news story (compared to Fig. 3) exhibits lower (compared to 17.03 in Fig. 3) pairwise node similarity and a lower Giant Connected Component average degree (4) compared to a big news story.
In short, the larger the average degree of a Giant Connected Component of a story graph, the bigger the news event, and vice versa.
StoryGraph generates 144 graphs (1 per 10 minutes) for a single day, this means there are 144 possible candidate (duplicate stories included) news graphs to pick from while selecting the top news story for a given day. The following steps were applied in order to select the top news story for a single day. First, each story graph was awarded a score, the score was derived from the average degree of the giant connected component in the graph. Second, from the set of 144 story graphs, the graph with the highest score was selected to represent the top news story for the day. This graph represents the graph with the giant connected component with the highest average degree. Steps 1 and 2 were applied across 365 days to generate the scores plotted in Fig. 1. Fig. 1 captures the top news stories for each of the 365 days in 2018.
The top news stories of 2018
From Fig. 1, and the table below, it is clear that the Kavanaugh hearings was the biggest news story of 2018 with GCC avg. degree of 25.85. In fact, this story was the top news story for about 25 days (red dots in Fig. 1). Also, the top story had three sibling story graphs with GCC avg. degrees (18.96 - 21.94) higher than the second top story.

Rank Date (MM-DD) News Story (Selected) Title GCC Avg. Deg
1 09-27 Kavanaugh accuser gives vivid details of alleged assault - CNN Video 25.85
2 02-02 Disputed GOP-Nunes memo released - CNNPolitics 18.81
3 06-12 Kim Jong Un, Trump participate in signing ceremony, make history: Live updates - ABC News 18.15
4 10-24 Clinton and Obama bombs: Secret Service intercepts suspicious packages - The Washington Post 17.03
5 03-17 Trump celebrates McCabe firing on Twitter - CNN Video 16.32
6 06-14 DOJ IG report 'reaffirmed' Trump's 'suspicions' of bias of some in FBI: White House - ABC News 15.63
7 08-29 A Black Progressive and a Trump Acolyte Win Florida Governor Primaries - The New York Times 15.37
8 04-14 Trump orders strike on Syria in response to chemical attack - ABC News 15.21
9 02-25 Trump calls Schiff a 'bad guy,' Democratic memo 'a nothing' - CNNPolitics 15.13
10 11-07 John Brennan Warns After Sessions’ Firing: ‘Constitutional Crisis Very Soon’ - Breitbart 14.88

The next major news story of 2018 was the news surrounding the release of Nunes' Memo (GCC avg. degree: 18.81). Similar to the Kavanaugh hearings, the story about the release of the controversial memo was the top news story for seven days. In contrast, the story about Schiff's rebuttal memo did not receive as much attention with rank 9 and GCC avg. degree of 15.13. In third place was the Trump-Kim summit with GCC avg. degree of 18.15. Unlike the top two stories, this story, although initially big, did not linger beyond two days. This is an example of a big news story that lacked staying power.

Multiple news stories in our list were included in the list of top stories from other news organizations such as CNNCBS, NBCNews, and BusinessInsider. For example, the Kavanaugh hearings (No. 1), the Trump-Kim summit (No. 3), the Pipe bomber (No. 4), and the Midterm elections (No. 7), were included in multiple top news lists. However, to our surprise the MSD shooting news story (GCC avg. degree of 7.74) was not in our list of top 10 new stories, even though it appeared in multiple top news lists from multiple news organizations. Also, the Nunes memo story (No. 2) was our second top story, but it was absent from the list of top news stories of the four major news organizations we considered.

President Trump was a dominant figure in the 2018 news discourse. As shown in Fig. 1, out of the 365 days, "Trump" was included in the title representing the story graphs 197 (~54%) times.

-- Alexander Nwala (@acnwala)