A Cornell sociologist has transformed the small world concept of "six degrees of separation" into a scientific sampling method for finding and studying "hidden populations," from drug users to jazz musicians.

The method can be used to obtain a scientifically valid, representative sample of populations that can't be identified using traditional sampling methods; these would include, for example, drug addicts, HIV-infected individuals, the homeless, runaway youths, gays and lesbians, poets and so on.

"There are no lists available or associations of runaway youths, for example. But this sampling method takes advantage of the fact that individuals in a group know each other. As we gather information during the sampling process of referrals, we look at the degree to which people tend to recruit those similar to them. Then, we can mathematically correct for the non-randomness and project what the sample would have been had there been no biases," says Douglas Heckathorn, professor of sociology at Cornell.

His paper on how this sampling method is being applied to finding jazz musicians, co-authored by Joan Jeffri, director of the Research Center for Arts and Culture at Columbia University Teachers College and director of the study, is published in a special issue of Poetics (November 2000). A shorter version of the paper, "Tracking the Invisible: Identifying Artist Populations," will be published in a forthcoming issue of the Proceedings of the International Association of Jazz Educators . Heckathorn and Jeffri will present the paper at a conference of this group of more than 4,000 individuals in January 2001.

Heckathorn developed and tested this so called "respondent-driven" sampling method -- a new form of chain-referral sampling -- to study a peer intervention program with drug users in Connecticut, Chicago and Russia. He now is applying his sampling method for a study of jazz musicians for the National Endowment for the Arts (NEA). The study seeks to determine the socio-economic profiles of these musicians, such as whether they have health and life insurance, data on copyright protection, use and abuse of new technologies, their level of income from jazz and jazz-related activities, number of jobs the musicians need to survive, their experiences with mentors, teaching, distribution, marketing and management and retirement.

"Jazz artists exist in a kind of no-man's land, where earning a living from jazz is almost impossible and where even individual support like the Jazz Masters awards from the NEA are not enough to offset the hand-to-mouth existence of most jazz musicians," says Heckathorn. Once the researchers obtain a statistically valid sample, they will seek to determine the musicians' current situation and most pressing needs.