snowball sample
n.— «Researchers pursue what is called a “snowball sample,” seeking out workers who then recruit their friends in a process they liken to a chain letter, or to the “six degrees of separation” theory of connectedness. A mathematical formula is applied to the sample like a “corrective lens,” Professor Heckathorn explained, to obtain a sample that is “theoretically independent of its nonrandom starting points.”» —“In Challenge to Survey Low-Wage Workers, Researchers Pursue ’Snowball Sample'” by Sam Roberts New York Times Apr. 15, 2006. (source: Double-Tongued Dictionary)
Further reading
National Book Award winner Barry Lopez had wise advice for young writers. First, read widely and follow your curiosity. Second, travel or learn a foreign language. And third, find out what you truly believe, because if you’re not writing from...
Twice a day the River Thames recedes, revealing a muddy shoreline. Hobbyists known as mudlarks stroll the surface searching for objects that have found their way into the river over the centuries, everything from ancient Roman jewelry to modern...