Booklet 4: Sampling

Question 1

What is a target population

Answer 1

The group of people that psychologists want to be able to generalise their findings to

Question 2

What is a sample

Answer 2

The group of people selected who represent the target population

Question 3

What is sampling

Answer 3

The process of selecting participants from the population

Question 4

What are the 4 methods of sampling

Answer 4

1. Opportunity Sampling
2. Volunteer Sampling
3. Random Sampling
4. Snowball Sampling

Question 5

What is Opportunity Sampling

Answer 5

Making use of the people that are readily available and willing to participate

Question 6

What are the strengths of Opportunity Sampling

Answer 6

• POINT - Is the easiest, quickest and most economical way to obtain participants, as the psychologist will use people that they have easy access to and they don’t have to pay for advertising
• COMMENT - Useful for gathering a representative sample and more time is spent exploring the behaviour

Question 7

What are the weaknesses of Opportunity Sampling

Answer 7

• POINT - Likely to produce a biased sample as only certain types of people will be selected from limited areas
• COMMENT - Sample will not be very representative of the target population

Question 8

What is Volunteer Sampling

Answer 8

The psychologist will place an advert then the people interested in the study would reply to the advert and the psychologist would filter the responses to collect a sample that reflected the target population

Question 9

What are the strengths of Volunteer Sampling

Answer 9

• POINT - Gives wide range of access to potential participants and it is also convenient and ethical if it leads to informed consent and people will be less likely to drop out
• COMMENT - More representative of the target population as a wider group of our target population may see the advert

Question 10

What are the weaknesses of Volunteer Sampling

Answer 10

• POINT - Often unrepresentative as it leads to a biased sample as people tend not to adverts unless they have a strong interest/view to share or a motivation to take part
• COMMENT - Limits the generalisability of the behaviour and can increase volunteer bias

Question 11

What is Random Sampling

Answer 11

• Every member of the target population has an equal chance of being selected
• The researcher needs the names of all members of his target population and all potential participants are entered into a draw and names are randomly selected until the desired number of participants is chosen
• Random number generator is usually used

Question 12

What are the strengths of Random Sampling

Answer 12

• POINT - This is the least bias method of sampling as all members of the target population have an equal chance of being selected
• COMMENT - Most representative sampling method meaning we can generalise behaviour to the target population

Question 13

What are the weaknesses of Random Sampling

Answer 13

• POINT - Is very difficult and time consuming to do, especially with large target populations
• COMMENT - Limits the potential size of the sample and therefore less generalisable to the target population

Question 14

What is Snowball Sampling

Answer 14

• Can be used if the population is not easy to contact
• Achieved by asking a participant to suggest someone else who might be willing or appropriate for the study
• e.g. truants, drug users, alcoholics etc

Question 15

What are the strengths of Snowball Sampling

Answer 15

• POINT - Possible to include members of groups where no lists or identifiable clusters even exist
• COMMENT - Therefore we are able to gather a sample that is it representative of the target population and therefore is generalisable to them

Question 16

What are the weaknesses of Snowball Sampling

Answer 16

• POINT - There is no way of knowing whether the sample is representative of the population