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Chapter 1: Introduction and Graphical Displays
15
Systematic Sample
This type of sampling procedure is used when a random sample is not
needed or it is not obtainable.
Definition: Systematic Sample
A systematic sample is obtained by selecting every
element in the
population to form the sample.
As an illustration, for example if we are interested in studying the
distribution of ACT math scores of freshmen at a college, then the
population of ACT math scores will be the ACT math scores of all freshmen
at that particular college. If we selected every tenth ACT math scores of
freshmen at the college, then this selected set will represent a systematic
sample of ACT math scores for the population of freshmen at that particular
college.
Figure 1- 8
shows the systematic sample for this illustration.
Figure 1- 8:
Illustration for a systematic sample.
There are some advantages and disadvantages of selecting a systematic
sample.
Advantages of a Systematic Sample
It is very simple to use to obtain a sample.
It ensures a good representation of the population.