Twitter data reveals the cities that set trends and those that follow. And the difference may be in the way air passengers carry information across the country, by-passing the internet, say network scientists
One
of the defining properties of social networks is the ease with which
information can spread across them. This flow leads to information
avalanches in which videos or photographs or other content becomes viral
across entire countries, continents and even the globe.
It’s
easy to imagine that these trends are simply the result of the
properties of the network. Indeed, there are plenty of studies that seem
to show this.
But in recent years,
researchers have become increasingly interested in the relationship
between a network and the geography it is superimposed on. What role
does geography play in the emergence and spread of trends? And which
areas are trend setters and which are trend followers?
Today
we get an answer of sorts thanks to the work of Emilio Ferrara and pals
at Indiana University in Bloomington. These guys have examined the way
trends emerge in cities across the US and how they spread to other
cities and beyond.
Their research allows
them to classify US cities as sources, those that lead the way in
trends, or those that follow the trends which the team call sinks.
Their
research also leads to a curious conclusion–that air travel plays a
crucial role in the spread of information around the country This
implies that trends spread from one part of the country to another not
over the internet but via air passengers, just like diseases.
The
method these guys use is straightforward. Twitter publishes a
continuously updated list pf the the top ten most popular phrases or
hashtags on its webpage. It also has webpages showing the trending
topics for each of 63 US cities.
To capture
the way these trends emerge and spread, Ferrra and co set up a web
crawler to check each list every ten minutes between 12 April and 30 May
2013. In this way the collected over 11,000 different phrases and
hashtags that became popular throughout these 50 days.
They
then plotted the evolution of these trends in each US city over time.
This allowed them to study how trends spread from one city to another
and to look for clusters of cities in which the same topics trend
together.
The results are revealing. They
say most trends die away quickly–around 70 per cent of trends last only
20 minutes and only 0.3 per cent last more than a day.
Ferrara
and co say they can see three distinct geographical regions that share
similar trends–the East coast, the Midwest and Southwest. It’s easy to
imagine how trends arise at a low level and spread through the region
through local links such as friends.
But
these guys say there is also a fourth cluster of influential cities that
also form a group where the emergence of trends is related. However,
these place are not geographically related. They are metropolitan areas
such as Los Angeles, New York, Atlanta, Chicago and so on.
What
links these places is not geography but airports, say Ferrara and co.
Their hypothesis is that topics trend in these places because of the
influence of air passengers. In other words, trending topics spread just
like diseases.
Ferrara and co have created a list of the cities that act as trend setters and those that act as trend followers.
The top five sources of trends are: Los Angeles, Cincinnatti, Washington, Seattle and New York.
The top five trend followers (or sinks) are: Oklahoma City, Albuquerque, El Paso, Omaha and Kansas City.
That’s
a fascinating result. In a sense it’s obvious that the large scale
movement of people will influence the apread of information However,
it’s not obvious that this should happen at a rate that is comparable to
the spread of trends across the internet itself.
And
it raises an interesting question that Ferrara and co hope to answer in
future work. “Does information travel faster by airplane than over the
internet?” they ask.
We’ll be watching for when they reveal the answer.
No comments:
Post a Comment