We used the Digg application programming interface (http://apidoc.
digg.com/) 4 to retrieve all diggs made
by registered users from July 1, 2007
to December 18, 2007. This data set included approximately 29 million diggs
by 560,000 users on approximately 2. 7
million submissions, a number including all past submissions receiving any
digg, not only the submissions during
the six months. The number of submissions was about 1. 3 million, of which
about 94,000 ( 7.1%) were promoted to
the front page.
YouTube is the apex of the Web’s
user-created video-sharing portals,
with (as of 2008) 65,000 new videos uploaded and 100 million viewed daily,
implying that 60% of all online videos
were watched through YouTube. 3, 6 It
was also the third most frequently accessed site on the Web, based on traffic rank. 1 Beginning April 21, 2008, we
collected view-count time series on
7,146 selected videos daily in the portal’s “recently added” section, carrying
out data collection for the next 30 days.
Apart from the list of “most recently
figure 1. average normalized popularity of submissions to Digg and you Tube by individual
popularity at day 30. The inset is the same measurement for the first 48 digg hours
of Digg submissions.
average normalized popularity
Time (digg hours)
0 10 20 30 40
added” videos, it also offered listings
based on such You Tube-defined selection criteria as “featured,” “most discussed,” and “most viewed.” We chose
the “most recently uploaded” list to
give us an unbiased sample of all videos submitted to the site or complete
history of the view counts for each video during its lifetime. YouTube’s API
overview.html) 10 provided programmatic access to several video statistics,
with view count at a given time being
one of them.
However, due to the fact that the
view-count field of a video did not appear to have been updated more often
than once a day by YouTube, we were
able to calculate only a good approximation of the number of daily views.
Worth noting is that while the overwhelming majority of video views was
initiated from the YouTube Web site
itself, videos might have been linked
from external sources as well, appearing as embedded objects on the referring page; while 50% of all videos in
2007 were thought to be linked externally, only about 3% of the views came
from these links. 2
figure 2. Daily and weekly cycles in the hourly rates of digging activity, story submissions,
and story promotions, respectively. To match the different scales, we multiplied the rates
for submissions by 10 and the rates of promotion by 1,000. The horizontal axis represents
the week august 6, 2007 (monday)–august 12, 2007 (Sunday). The tick marks are midnight
on the respective day, Pacific Standard Time.