Mind map 4.2: Kinds of sampling
Mind map 4.3 below illustrates the different types
of sampling design, followed by Mind
map 4.4 illustrating.
Mind map 4.3: Types of sampling design
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Probability
sampling
Simple random sampling
• Each element in the population has an equal and independent chance of selection
as part of the sample.
• There is no bias or predetermination in the selection process.
For instance, in simple random sampling, if the researcher decides to choose every fifth
element in the sampling frame, that is, the actual list of the elements from which the sample
is actually drawn, ideally the complete and correct list of population members only, then
there is no independent randomness in the selection process.
The process of random sampling consists of four basic steps:
• Define of the population clearly
• List all members/elements of the population
• Number the elements of the population
•
Select the sample, use an approach that guarantees randomness.
For the actual sample selection, use a table of random numbers or a computer program to
generate samples. Often, simple random sampling is not practical as it requires a complete
list of a population which is not always possible.
Systematic sampling
Systematic sampling is a method of probability sampling where
the target from the larger
population is chosen according to a random starting point but with fixed periodic interval.
• The interval is calculated=
Systematic sampling is one statistically valid alternative. In this approach element in the
population is sampled, beginning with a random start of an element in the range of one.
Systematic sampling is simpler
than simple random sample; however, it may not be as
exact as simple random sampling in the randomness and independence of the selection
procedure.
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