Professor Howlick's questionnaire asked each student to name every other student with whom they had drank with during the past two months. Kerry Sobiski, his assistant, sent emails for the online survey to each person named by students in the first sample. The same question was asked in this online survey. Ms. Sobiski next sent emails for the online survey to everyone named as a drinking partner in the second sample and so on until she had emailed ten different waves of online surveys. She then drew up a list of all students who drank with anyone else who answered the online survey, and used it as a sample for a study on drinking networks on campus. What kind of sampling was Ms. Sobiski using?
A) snowball sampling
B) quota sampling
C) accidental sampling
D) cluster sampling

Snowball sampling

Explanation: Snowball sampling also called chain referral sampling occurs when a research participants request the assistance of other participants for a test or study. It is used where potential participants are hard to find. In snowball sampling a researcher picks the first few samples and either recruits them or asks them to recommend other subjects they know who fit the description of samples needed. This referral technique goes on and on, increasing the size of the respondent population like a snowball rolling down a hill until the researcher has sufficient data to analyze. It's called snowball sampling because once you have the ball rolling, it picks up more “snow” along the way and becomes larger and larger. As evident in the above question Kerry Sobiski employed the assistant of students to recommend other students they have drank with in the past two month, this assistant cascaded further until sufficient enough data was gardered. Without doubt this sampling method is the snowball sampling method.