Social Research Methods: Qualitative and Quantitative Approaches

QUALITATIVE AND QUANTITATIVE SAMPLING

have had sexual relations with each other. The cru-
cial feature is that each person or unit is connected
with another through a direct or indirect linkage.
This does not mean that each person directly knows,
interacts with, or is influenced by every other per-
son in the network. Rather, taken as a whole, with
direct and indirect links, most people are within an
interconnected web of linkages.
For example, Sally and Tim do not know each
other directly, but each has a good friend, Susan, so
they have an indirect connection. All three are part
of the same friendship network. Researchers repre-
sent such a network by drawing a sociogram,a dia-
gram of circles connected with lines. The circles
represent each person or case, and the lines repre-
sent friendship or other linkages (see Figure 5).
Snowball sampling(also called network,
chain referral, reputational,and respondent-driven
sampling) is a method for sampling (or selecting)
the cases in a network. The method uses an analogy
to a snowball, which begins small but becomes
larger as we roll it on wet snow and it picks up addi-
tional snow. Snowball sampling is a multistage
technique. It begins with one or a few people or
cases and spreads out based on links to the initial
cases.
For example, we want to study friendship net-
works among the teenagers in our community. We
might start with three teenagers who do not know
each other. We ask each teen to name four close
friends. Next we go to each set of four friends and
ask each person to name four close friends. This
continues to the next round of four people and
repeats again. Before long, a large number of people
have been identified. Each person in the sample is
directly or indirectly tied to the original teenagers,
and several people may have named the same per-
son. The process stops, either because no new
names are given, indicating a closed network, or
because the network is so large that it is at the limit
of what can be studied. The sample includes those
named by at least one other person in the network
as being a close friend.

Deviant Case Sampling

We use deviant case sampling(also called extreme
case sampling) when we are interested in cases that

differ from the dominant pattern, mainstream, or

predominant characteristics of other cases. Similar

to purposive sampling, we use a variety of tech-

niques to locate cases with specific characteris-

tics. The goal is to locate a collection of unusual,

different, or peculiar cases that are not representa-

tive of the whole. We select cases because they are

unusual. We can sometimes learn more about

social life by considering cases that fall outside the

general pattern or including what is beyond the

main flow of events.

For example, we want to study high school

dropouts. Let us say that previous research suggested

that a majority of dropouts come from low-income,

Jian

Anne

Maria

Chris

Bill

Bob Kumiko

Pat

Paul

Sally

Joyce

Muhammed

Tim

Jorge Susan Larry

Dennis

Donna Ebony

Note: Shading indicates various skin tones.

FIGURE 5 Sociogram of Friendship Relations

Snowball sampling A nonrandom sample in which

the researcher begins with one case and then, based

on information about interrelationships from that case,

identifies other cases and repeats the process again and

again.

Deviant case sampling A nonrandom sample, espe-

cially used by qualitative researchers, in which a

researcher selects unusual or nonconforming cases

purposely as a way to provide increased insight into

social processes or a setting.