Sampling

Question 1

what is the target population?

Answer 1

a group of people who are the focus of the researcher’s interest from which a smaller sample is drawn

Question 2

what is a sample?

Answer 2

a group of people from the target population

Question 3

what should a sample be?

Answer 3

should be representative of the target population so that findings can be generalized to the entire target population

Question 4

what are the different types of sampling techniques?

Answer 4

random
opportunity
stratified
volunteer

Question 5

what is random sampling?

Answer 5

all members of the target population have an equal chance of being selected

1. A complete list of all members of the target population is obtained
2. All the names on the list are assigned a number
3. The sample is generated using some sort of lottery method (e.g. computer random number generator or picking numbers out of a hat)

Question 6

strengths and weaknesses of random sampling

Answer 6

+ A random sample is free from bias – the researcher has no influence over who is selected and all members of the target population have an equal chance of selection
+ This sampling technique is the most likely of all to lead to a representative sample

• The researcher may still obtain an unrepresentative sample (e.g. More females than males)
• Very time consuming and difficult to conduct – a complete list of the target population is hard to obtain

Question 7

what is opportunity sampling?

Answer 7

Involves using people who are readily available to the researcher
The researcher approaches people who happen to be available at the time and asks them if they are willing to take part in the research
E.g. Those in the cafeteria at George Abbot School

Question 8

strengths and weaknesses of opportunity sampling

Answer 8

+ Very convenient method as it requires less time and effort - you use the first participants you can find
+ Less costly – no randomizing technology needed

• Unrepresentative of the target population as it’s taken from a small part of the target population (e.g. just students who are in the cafeteria during lunch, not all students will be there)
  Researcher bias as he/she has complete control over participant selection (they might avoid someone they don’t like the look of)

Question 9

what is stratified sampling?

Answer 9

the composition of the sample reflects the proportions of people in certain sub-groups (strata) within the target population

researcher identifies the different strata that make up the population
proportions needed for the sample to be representative are worked out.
finally, the participants that make up each stratum are selected using random sampling.

Question 10

strengths and weaknesses of stratified sampling

Answer 10

+ More representative than opportunity sampling because each sub-group is represented equally
+ Avoids researcher bias –once the target population has been sub-divided into strata, the participants are then randomly selected

Question 11

what is volunteer sampling?

Answer 11

Involves participants selecting themselves to be a part of the sample (also known as ‘self-selection’)
Researcher may place an advert in a newspaper or in the common room noticeboard at school
It could be as simple as putting your hand up to volunteer when the researcher asks

Question 12

strengths and weaknesses of volunteer sampling

Answer 12

+ You have access to a variety of participants (e.g. all people who use the common room) which would make the sample less biased and more representative than opportunity sampling
+ Very easy – ‘they come to you’ so minimal effort from the researcher

• Biased sample – participants are likely to have more time on their hands and be highly motivated individuals (called volunteer bias)
• Volunteer bias affects how far the findings can be generalized