Antti Ukkonen, a postdoctoral researcher at HIIT, was awarded the Frontier Prize at the 13th International Symposium on Intelligent Data Analysis (IDA 2014) for his work on estimating the distribution of shortest path lengths in real-world social networks.
The awarded paper makes an attempt to take a fresh look at the so called "six-degrees of separation" phenomenon. A famous study about this is an experiment conducted by Jeffrey Travers and Stanley Milgram in the 1960s. A very similar experiment was repeated later in the early 2000s by Dodds, Muhamad and Watts.
These experiments show that short paths to the target person exist, and that the participants are able to find them using only "local" information about their friends. However, they do not uncover the true shortest path distribution of the underlying social network. This is because of two reasons. First, long paths are less likely to be found as messages get discarded on the way (some people don't forward the message). Second, the participants are unaware of the true shortest paths.
The awarded paper proposes a model that tries to account for these effects. It produces estimates both for the "skill" of the participants, as well as the true underlying shortest-path distribution. When the data of Travers & Milgram (TM) are compared to those of Dodds et al. (DMW) using the new model, we find that participants to the TM experiment were more skilled at forwarding the message, while the social network estimated from the DMW experiment has a lower average shortest path length. In the DMW experiment the participants used email, which may have made them think less about their choice of the next recipient. Also, perhaps the world indeed had become "smaller" during the approximately 40 years in between the experiments, as the decrease in the average path length suggests.
The full paper titled "Indirect estimation of shortest path distributions with small-world experiments" can be found here: http://anttiukkonen.com/pdf/iespdusme.pdf
About the author: Antti Ukkonen has been working at HIIT since September 2012. Prior to that he was a postdoctoral researcher at Yahoo! Research Barcelona. Antti obtained his doctoral degree from Helsinki University of Technology in 2008.
Last updated on 4 Nov 2014 by Michael Mathioudakis - Page created on 4 Nov 2014 by Michael Mathioudakis