Points to remember
The following are the major points introduced in this chapter. Ensure that you are very confident with their meaning, content, context and significance.
1
Sampling is the process of choosing the respondents and the units of the study
in general.
2
Sampling is a common practice and an indispensable research tool in social
sciences.
3
Sampling, as the alternative to conducting a saturation survey, offers many
advantages.
4
Sampling units must be chosen objectively and systematically, must be easily
identifiable and clearly defined, independent from each other, not
interchangeable, and free of errors, bias and distortions.
5
The two distinct types of sampling are probability and non-probability sampling.
6
In a probability sampling, all units have an equal, calculable and non-zero
probability to be included in the sample.
7
Non-probability sampling does not adhere to the rules of probability.
8
The two types of probability sampling are simple random sampling and systematic
sampling.
9
In a simple random sampling all units of the target population have an equal
chance of being selected.
10
The three most common techniques of selection used in simple random sampling are
the lottery method, the method of random numbers and the computer method.
11
In systematic sampling although all units have an equal chance of being
selected, their selection depends on the choice of other units.
12
Systematic sampling employs the sampling fraction method of choosing the
respondents.
13
Stratified random sampling is the procedure in which the sample is chosen after
the target population is divided into a number of strata, from which the
respondents are taken.
14
Cluster sampling is the procedure in which in the first instance clusters are
chosen.
15
In multi-stage sampling, samples are chosen in stages: firstly one sample is
taken and then a second or third sample is chosen from within the previous
sample.
16
In multi-phase sampling the procedure followed is the same as in multi-stage
sampling with the difference that in each stage of sampling data is collected.
17
Area sampling is the procedure in which the choice of respondents is related to
geographical areas. An area is divided into smaller sections, progressively
leading to smaller samples and ultimately to the respondents.
18
Panel samples include a number of respondents chosen in a systematic way and
subjected to data collection on more than one occasion.
20
Spatial sampling is a procedure in which a sample is taken from people
temporarily congregated in space.
21
Accidental sampling is a non-probability sampling procedure in which the
researcher chooses a number of respondents at will. It is also called
convenience sampling, chunk sampling, grab sampling or haphazard sampling.
22
In purposive sampling the researcher chooses the respondents who are thought to
serve the purpose of the study. It is also called judgmental sampling.
23
Quota sampling is the procedure in which the researcher chooses a quota of
respondents set by the project manager.
24
Snowball sampling is a procedure in which the selection of additional
respondents is guided by respondents who have already been studied.
25
In theoretical sampling the choice of respondents is guided by the emerging
theory.
26
Sampling procedures are employed in all quantitative studies but elements of
sampling are found also in qualitative research.
27
Non-response is a serious research problem that investigators must deal with.
28
Sample size is computed by means of statistical and non-statistical procedures.