Sampling

Question 1

Random Sample

Answer 1

A sophisticated form of sampling in which all members of the target population have an equal chance of being selected

Question 2

How to do a random sample?

Answer 2

1. Obtain a complete list of all members of the target population
2. Assign each name a number
3. Sample is generated through the use of a lottery method

Question 3

‘Lottery methods’

Answer 3

• Pick numbers out of a hat

- Computer based randomiser (only use if completely necessary; best to use a manual method)

Question 4

Random Sampling

Strengths

Answer 4

• Free from researcher bias; no influence over who is selected

Question 5

Random Sampling

Limitations

Answer 5

• Difficult, time consuming to conduct
• A complete list of the TP may be hard to obtain
• Sample may still be unrepresentative
• Selected PPs may refuse to take part

Question 6

Systematic Sample

Answer 6

When every nth number of the TP is selected

Question 7

How to do a systematic sample?

Answer 7

1. A sampling frame is produced
2. A sampling system is nominated/determined randomly to reduce bias
3. Researcher works through sampling frame until complete

Question 8

‘Sampling frame’

Answer 8

A list of people in the TP organised - eg. into alphabetical order

Question 9

Systematic Sampling

Strengths

Answer 9

• Avoids researcher bias

- Fairly representative

Question 10

Systematic Sampling

Limitations

Answer 10

• There is still the probability of getting an unrepresentative sample (unlikely)

Question 11

Stratified Sample

Answer 11

The composition of the sample reflects the proportion of people in certain strata within the TP or wider population

Question 12

‘Strata’

Answer 12

Sub-groups

Question 13

How to do a stratified sample?

Answer 13

1. Researcher first identifies the different strata that make up the population
2. Proportions needed for the sample to be representative are worked out
3. The participants that make up each stratum are selected using random sampling

Question 14

Stratified Sampling

Strengths

Answer 14

• Avoids researcher bias: once the TP has been subdivided into strata, the PPs are randomly selected
• Representative sample as it is designed to accurately reflect the composition of the population
• Generalisation of findings becomes possible

Question 15

Stratified Sampling

Limitations

Answer 15

• Not perfect; the strata can’t reflect all the ways that people are different. Complete representation of the TP is impossible

Question 16

Opportunity Sample

Answer 16

A sample where researchers select anyone who happens to be willing and available

Question 17

How to do an opportunity sample?

Answer 17

1. Researcher simply takes the chance to ask whoever is around at the time of their study

Question 18

Opportunity Sampling

Strengths

Answer 18

• Convenient; less time and effort

- Less costly

Question 19

Opportunity Sampling

Limitations

Answer 19

• Unrepresentative of TP as it is drawn from a very specific area
• Researcher bias

Question 20

Volunteer Sample

Answer 20

Participants select themselves to be part of the sample, hence aka ‘self-selection’

Question 21

How to do a volunteer sample?

Answer 21

1. Researcher may place an advert or willing PPs may volunteer when researcher asks

Question 22

Volunteer Sampling

Strengths

Answer 22

• Easy; minimal input is required from researcher

- Less time-consuming

Question 23

Volunteer Sampling

Limitations

Answer 23

• Volunteer bias
• May attract a certain ‘profile’ of a person (helpful, keen, curious)
• Can affect how far findings can be generalised