Sampling

Question 1

What is a population?

Answer 1

A large group of individuals that a particular researcher is interested in studying

Question 2

What is a sample?
Why do we use them?

Answer 2

A small selection of people from the population.
We use samples because they are more economical than using entire populations.

Question 3

Why do samples need to be representative?

Answer 3

So we can generalise findings to the whole population.

Question 4

Name the 5 types of sampling.

Answer 4

Systematic
Random
Stratified
Opportunity
Volunteer

Question 5

How do we do random sampling?
Name the technique we use to randomly select people.

Answer 5

All members from the target population are listed. The names of the people are then randomly selected using a random generator or a hat. This is called the lottery method technique.

Question 6

Why do random samples have high internal validity?

Answer 6

Samples are chosen in an unbiased way, therefore CVs and EVs should be randomly divided between groups

Question 7

Why is random sampling difficult and time consuming?

Answer 7

A complete list of the target population is hard to obtain.

Question 8

Why might random samples still be unrepresentative?

Answer 8

Probability cannot guarantee that all PPTs will be different and therefore representative of a population.

Question 9

Why might random sampling actually be more similar to volunteer sampling?

Answer 9

People randomly selected from the target population may refuse to take part.

Question 10

What is a systematic sample?

Answer 10

Where every nth member of the target population is chosen.

Question 11

What is a sampling frame?
How can be created to avoid bias?

Answer 11

A list that the target population is organised into.
May be listed in alphabetical order or the first member in the list may be assigned using a random generator.

Question 12

Explain the strength of systematic sampling being objective.

Answer 12

The researcher has no influence over who is chosen from the sampling frame once it has been established.

Question 13

Why might systematic sampling be more similar to volunteer sampling?

Answer 13

Some PPTs may refuse to take part.

Question 14

What is a stratified sample?

Answer 14

A form of sampling where the composition of the sample reflects proportions of certain people within the population.

Question 15

What are strata?

Answer 15

Different subgroups within the population.

Question 16

How are the strata within a stratified sample made to be representative?

Answer 16

We find the percentage of people within the main population who are in each of the strata.
We then get a smaller sample ensuring the percentage of each strata is present within the population.

Question 17

Why does stratified sampling allow generalisation?

Answer 17

The strata are likely to accurately represent the real population.

Question 18

Why is complete representation of populations not always possible with stratified sampling?

Answer 18

The strata cannot possibly represent all differences within a population.

Question 19

What is opportunity sampling?

Answer 19

A type of sampling where the sample is chosen based off who is available and willing at the time.

Question 20

Explain the economical advantages of opportunity sampling.

Answer 20

It is convenient, cheap and not time consuming because a list of the target population is not required.

Question 21

Why can’t findings from an opportunity sample be generalised?

Answer 21

Only a small group of people will be studied. They may all have similar qualities, such as being from the same school, so will not reflect the whole population.

Question 22

Why might opportunity sampling lead to researcher bias?

Answer 22

The researcher has complete control over who they choose to take part in the experiment.

Question 23

What is volunteer sampling?
How might PPTs hear about a sample being needed?

Answer 23

PPTs select themselves to be part of the sample.
They may do this after seeing an advert or a poster etc

Question 24

Why is volunteer sampling easy for researchers?

Answer 24

All PPTs come to you and ask to take part, therefore it requires minimal effort.

Question 25

What are the benefits of using PPTs who have volunteered?

Answer 25

They are likely to be more engaged and interested in the study.

Question 26

What are the issues with volunteer bias in volunteer sampling?

Answer 26

Volunteer sampling may attract certain types of people, such as those who try and please the researcher. This means that PPT behaviour will be unnatural and results won’t be fully accurate and generalisable.