Sampling

Question 1

Define what a population is.

Answer 1

Group which is the focus of the researcher, from which a smaller sample is drawn

Question 2

Define what a sample is.

Answer 2

Group of people who take part in an experiment.

Drawn from a target population and presumed to be representative of that population.

Question 3

Define sampling technique.

Answer 3

Method used to select people from a population.

Question 4

Define bias in the context of sampling.

Answer 4

When certain groups are over/under represented within the sample.

E.g. too many youngsters - limits generalisation

Question 5

Define generalisation.

Answer 5

Extent to which findings and conclusions from an experiment can be applied to the broader population.
This is possible if the sample is representative of the population.

Question 6

What is a random sample?

How is it carried out?

Answer 6

Form of sampling where all participants are equally likely to be picked.

• Make a list of all participants
• Assign a number to each name
• Choose the sample through a lottery method - put all numbers in hat and choose or put into a computer random number generator

Question 7

What is a systematic sample?

How is it carried out?

Answer 7

When every nth participant is selected.

• Create a sampling frame where participants are organized, e.g. by alphabet
• Randomly choose interval to prevent bias
• Work through sample frame until sample is complete

Question 8

What is a stratified sample?

How is it carried out?

Answer 8

Composition of sample reflects strata (sub-groups) of the target population.

• Identify the strata in the population
• Work out proportions needed for sample

Question 9

What is an opportunity sample?

How is it carried out?

Answer 9

Anyone is selected who’s willing and available.

• Researcher asks whoever is around at the time

Question 10

What is a volunteer sample?

How is it carried out?

Answer 10

Participants are self-selected.

• Researcher gains participants through a newspaper advert
• PPs simply raise hands when researcher asks.

Question 11

Evaluate random sampling.

Answer 11

Strengths:
+ No researcher bias: researcher has no influence over who is selected

Weakness:

• Difficult and time-consuming
• Sample may still not be representative of target population - still a chance a similar profile of person is chosen in the sample
• Selected participants may refuse to take part so could end up with slightly volunteered sample

Question 12

Evaluate systematic sampling.

Answer 12

Strengths:
+ No researcher bias: Once system for selection is established, researcher has no influence over who’s chosen
+ Fairly representative - possible but very unlikely selected participants will be similar to each other

Weakness:
- Selected participants may refuse to take part so could end up with slightly volunteered sample

Question 13

Evaluate stratified sampling.

Answer 13

Strength:
+No researcher bias: Once target population is divided into strata, PPs are randomly selected so researcher has no influence
+ Representative sample bc it’s designed to reflect the composition in the population - so can generalise findings

Weakness:
- Strata don’t reflect all the differences between people so complete representation of population isn’t possible

Question 14

Evaluate opportunity sampling.

Answer 14

Strength:
+ Convenient - saves researcher time and effort and cheaper than other sampling methods

Weakness:

• Sample is unrepresentative of target population as it’s made from a specific area, e.g. one street in one town, so can’t generalise findings
• Researcher bias - researcher chooses participants which will be based on the researcher’s own personality

Question 15

Evaluate volunteer sampling.

Answer 15

Strength:
+ Easy to conduct
+ Requires minimal input from researcher, so less time consuming than other sampling methods

Weakness:
- Volunteer bias - asking for volunteers may attract a specific profile of person e.g. one that is helpful and curious. Due to this, findings will lack generalisability.