http://smallworld.columbia.edu/index.html

In class we discussed Stanley Milgram’s famous experiment that attempted to test the small-world hypothesis. Although his experiment lead to the coining of the famous phrase “Six degrees of separation,” we also mentioned that his results were not particularly compelling for several reasons (e.g. Targets were people of high or notable status and many of the chains never reached the target). Attempts to replicate or conduct similar experiments have proven difficult and/or more restricted to a smaller network, but there is one that aims to discover whether or not the small-world property is indeed real.

The Small World Project, lead by Duncan J. Watts and others at Columbia University, is a large-scale experiment that uses email instead of regular postal mail to try to find targets. The basic rules still apply: participants are given some information about their assigned target but are not allowed to email them directly unless they know them personally; they can only pass on the message via email to a mutual acquaintance in effort to get the message “closer” to their target.

The project also expands upon Milgram’s experiment in a few ways. First, targets are chosen at random; some targets have included a professor from America, an Australian policeman, and a veterinarian from Norway (http://www.newscientist.com/article.ns?id=dn4037). This tests to see if “six degrees of separation” is applicable to arbitrary and “lower-status” targets. Second, participants are allowed to send multiple emails for the same target, as long as each person they send to is a mutual acquaintance. Since participants have to fill out information about each person they send to, how they know each other, and why they chose to send an email to them (as well as demographic information about themselves), spamming is not a major concern. Third, the project also seeks to analyze the “distribution of lengths, along with the effect of race, class, nationality, occupation, and education,” in addition to average length in general.

So far the project has estimated that for chains that started and ended in the same country, the average length was about 5, and for those that ended in different countries, the average was close to 7 (http://www.sciencemag.org/cgi/content/full/301/5634/827?ijkey=Evqpw33fK8Y.2&keytype=ref&siteid=sci).

In lecture we talked a little bit about how replicating Milgram’s experiment would be impractical, mainly because participation rates would be low. The Small World Project, however, has taken measures that helped achieve its success in obtaining substantial participation. First, the first people that start every chain volunteer themselves by signing up on the website; thus the dropout rate at the first step is low. Second, email is quick and more convenient than postal mail, which means that more people may be willing to take the small amount of time to participate if they receive an email from a previous person in the chain. Third, all emails and communications relevant to the experiment are done on the project site itself, which makes it more trustworthy, especially since the site is hosted on Columbia University.