Kumar-2011-Research-Methodology_-A-Step-by-Step-Guide-for-Beginners

Chapter 12: Selecting a sample 205
NT
WA
QLD
SA
NSW
= University
= University of technology
= College of advanced education
= TAFE
VIC
TAS
Figure 12.6 The concept of cluster sampling
every state and territory of Australia. In addition, there are different types of institutions,
for example universities, universities of technology, colleges of advanced education and
colleges of technical and further education (tafe) (Figure 12.6). Within each institution various
courses are offered at both undergraduate and postgraduate levels. Each academic
course could take three to four years. You can imagine the magnitude of the task. In such
situations cluster sampling is extremely useful in selecting a random sample.
The first level of cluster sampling could be at the state or territory level. Clusters could
be grouped according to similar characteristics that ensure their comparability in terms
of student population. If this is not easy, you may decide to select all the states and
territories and then select a sample at the institutional level. For example, with a simple
random technique, one institution from each category within each state could be
selected (one university, one university of technology and one tafe college). This is based
upon the assumption that institutions within a category are fairly similar with regards
to student profile. Then, within an institution on a random basis, one or more academic
programmes could be selected, depending on resources. Within each study programme
selected, students studying in a particular year could then be selected. Further, selection
of a proportion of students studying in a particular year could then be made using the
SRS technique. The process of selecting a sample in this manner is called multi-stage
cluster sampling.