The tweeting population of a city is a intriguing group. Its hard to pin point what intrinsically drives them to tweet, but what matters is when they collectively tweet about some topic — it shows up on Twitter’s trending topic list (TTL). For many of us, an easy way to be informed about ‘whats happening in the world’ — is by tracking the Twitter trending topics.

The TTL of a city (e.g., New York) is considered to be reflective of topics that have captured the city’s attention (here is how Twitter’s algorithm calculates what’s trending). The assumption is that sustained trending nature of some topic is a proxy for ‘sustained attention’ on that topic.

But more often than not, questions arise around why an event happening in the real world — is NOT trending on Twitter.

More on the geographical dispersion of #FreddieGray below, and why it did not trend nationally.

There are the usual suspects as to why something isn’t trending on Twitter: not enough media coverage, lack of consolidated hashtag usage, competing news stories or perhaps algorithmic censorship. But these conjectures is just the tip of the iceberg when it comes to geographical trend dispersion on Twitter.

As you can see, people are not happy about things ‘not trending’ on Twitter.

Recently, we published a paper (preprint here) called ‘The Attention Automaton’. In it we show how to model, to a significant extent, the Twitter trending ecosystem with respect to different geo-locations and specific categories of trends. We found that geographical trend dispersion is primarily determined by three factors: the information category of the topic, the attention shift tendency of the location and the initial persistence of the trend.

Given sufficient information about these factors, it could be possible to identify ‘The Perfect Seed’: a single (home) location for the trending topic where it must persist initially in order gain momentum and in time trend everywhere, eventually exploding into national attention.