Sampling techniques

Question 1

What is the target population?

Answer 1

The group of people from whom the sample is drawn

Question 2

What is a sample?

Answer 2

A small group from the population that you study

Question 3

What does it mean if a sample is representative?

Answer 3

You can generalise the results of your study to the wider population

Question 4

What is opportunity sampling?

Answer 4

Taking a sample from people who are available at the time the study is carried out and for the criteria you are looking for (e.g. Investigating school children and you stand at the door and ask the people who walk past you)

Question 5

What is volunteer sampling?

Answer 5

Participants becoming part of the study because they volunteer when asked or in response to an advert

Question 6

What is random sampling?

Answer 6

Every member of the population has an equal chance of being chosen (e.g. random number generator or names out of a hat), has no bias

Question 7

What is systematic sampling?

Answer 7

Using a predetermined system to select the sample (e.g. Select every 10th person from a list, the numerical interval is applied consistently)

Question 8

What is stratified sampling?

Answer 8

Involves classifying the population into categories and then choosing a sample which consists of participants from each category in the same proportions as they are in the population (e.g. making sure the proportions of male to female in your same is the same to the proportions in the population)

Question 9

What is strata?

Answer 9

Subgroups within a population e.g. Age group, gender

Question 10

What is a strength and weakness of opportunity sampling?

Answer 10

S - Easy and quick compared to random and stratified
W - Drawn from a small part of target population so biased

Question 11

What is a strength and weakness of random sampling?

Answer 11

S - Not very bias, high representative sample - everyone has an equal chance of being selected
W - More time-consuming and costly than opportunity and volunteer and some people may end up refusing to take part if selected.

Question 12

What is a strength and weakness of systematic sampling?

Answer 12

S - Unbiased
W - May have “Periodic traits” - the process of selection can interact with a hidden periodic trait within the population, if this happens the sampling technique is neither random, nor representative of the target population.

Question 13

What is a strength and weakness of stratified sampling?

Answer 13

S - Likely to be the most representative becuase you include the proportions, also unbiased.
W - Time consuming and costly and people might turn you down

Question 14

What is a strength and weakness of volunteer sampling?

Answer 14

S - Get variety in terms of some variables e.g. age, intelligence
W - Volunteers are a certain type of person so lack variety here (extroverted, enthusiastic, motivated etc) = “volunteer bias”