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Sampling refers to a group of people taking part in a
market research survey selected to be representative of
the target market overall
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Types of sampling
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Random
Quota
Stratified
Cluster
Snowballing
Sampling errors refer to errors in research caused by using
a sample for data collection rather than the whole target
population
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Each member of the population has an
equal chance of being included in the
sample
Everyone has an equal chance – this might
reduce bias
 Quite easy

Could select people who are not part of
target group
 May not get representative results

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Each Population is segmented into mutually
exclusive sub-groups (e.g. male/female). From
these groups, a certain number of people are
selected to part of the sample

Sample can be obtained quickly and cheaply
More reliable than random sampling
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
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Not always representative of the population
Sampling errors could occur because not
everyone has an equal chance to be sampled
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Involves segmentation (segments =
strata). Participants are chosen from
each group but in a way that is
proportional to the population

Samples are more representative of
target market

Can be difficult to select strata
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If the population is too far spread, market
researchers will sample indiviudal groups,
known as clusters. i.e. from just a few
lcoations

Quick and easy, relatively cheap
Bias and sampling errors (sometimes people
living in same area share similar
views/characteristics)
 May not get representative results
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The first respondent refers a friend…who
then refers another friend…who then
refers another friend…etc
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Cheap
Easy to get contact details of
respondents

Tends to be very biased
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As with all things, there are limitations to
sampling. The main drawback of
sampling is errors. We can categorize
these errors into non-sampling errors and
sampling errors.
› Differentiate between the two types of errors
› Explain why sampling errors could occur