sampling

Question 1

what is random sampling?

Answer 1

Every member of the target
population is identified and
the sample is randomly
selected.

Question 2

pros and cons random sampling

Answer 2

Likely to be representative so
can be generalised to the
target population.
- Difficult and time consuming
to get the full details of the
target population.
- People that are selected may
be unwilling to take part.

Question 3

what is systematic sampling?

Answer 3

Every Nth person (e.g. 10th,
15th, 25th…) is selected from
a register, phonebook, etc.

Question 4

pros and cons of systematic

Answer 4

• Not subject to researcher bias= without any personal
  preference from the
  researcher = each person is given a number
• Not truly unbiased as every
  Nth person selected may have
  a similar trait in common and
  therefore will not be
  representative of the wider
  population.

Question 5

what is stratified sampling?

Answer 5

A subgroup within the
population is identified (e.g.
gender or ethnic origin).
Participants are obtained in
proportion to their
occurrence within the
population.

Question 6

pros and cons of stratified

Answer 6

• Likely to be representative as
  each subsection of the target
  population is proportionally
  represented, so results can be
  generalised to the wider
  population with more
  confidence that they apply.
• Difficult and time consuming
  to identify subgroups.
• People that are selected may
  be unwilling to take part.

Question 7

what is opportunity sampling?

Answer 7

Selecting participants who are available and willing to take part.

Question 8

pros and cons of opportunity

Answer 8

Quicker and easier to obtain, in comparison to other methods.
- High chance that sample will
be biased, e.g. often use
available university students,
who are not representative of
the target population.

Question 9

what is volunteer sampling?

Answer 9

Participants self‐select by
responding to an advert.
They offer to take part.

Question 10

pros and cons of volunteer

Answer 10

• Quicker and easier to obtain, in comparison to other methods.
• A particular type of person is
  likely to take part in research
  (and also only those who see
  the advert). Therefore, the
  sample is likely to be biased.