Sampling Techniques

Question 1

Random sampling

Definition and Example

Answer 1

• Every member of the population has an equal chance of being selected
• Names pulled out a hat

Question 2

Random Sampling

Strengths and weaknesses

Answer 2

S- sample is likely to be very representative, researcher bias is not possible
W- the sample may still be unrepresentative, especially if it is small

Question 3

Opportunity sampling

Definition and example

Answer 3

• obtaining people who are available at a certain time/place to take part
• e.g selecting student who happen to be walking passed the library at 12:30

Question 4

Opportunity sampling

Strengths and weaknesses

Answer 4

S - a very fast way to gather participants. Less time, money and resources
W - the sample is drawn from a very narrow part of the target population

Question 5

Volunteer sampling

Definition and examples

Answer 5

• p’s self select by responding to an ad placed in a strategic place
• e.g. people responding to an advert placed in a sports center

Question 6

Volunteer sampling

Strengths and Weaknesses

Answer 6

S - requires minimum input, the p’s come to you. Ethical

W - volunteers are already motivated to engage, it attracts certain people

Question 7

Systematic sampling

Definition and example

Answer 7

• every nth member of the target population is selected and placed in different conditions
• e.g list all 500 names, pick every 10th person, get a sample of 50

Question 8

Systematic sampling

Strengths and weaknesses

Answer 8

S - p’s selected should, in theory, be representative and unbiased
W - the system doesn’t guarantee representativeness

Question 9

Stratified sampling

Definition and example

Answer 9

• identify key stratum (layers), calculate correct proportions for each based on target group, samples then selected randomly
• e.g if 12% of the group are aged between 20-30, in a sample of 100 there should be 12 p’s aged between 20-30

Question 10

Stratified sampling

Strengths and weaknesses

Answer 10

S - end up with an extremely representative sample

W - time consuming and difficult to execute