Statistics

Question 1

Opportunity Samply definition? Examples?

Answer 1

Opportunity sampling is choosing respondents based upon their availability and convenience

e.g Someone asking questions to neighbours about the area they live in/ their favourite football teams (not representative)

Question 2

Simple Random Sample definition? Examples?

Answer 2

In simple random sampling every possible sample has an equal chance of being selected

e.g Random number generator (being assigned to people) or lottery machines

Question 3

Systematic Sampling definition? Examples?

Answer 3

Systematic Sampling means taking participants at regular intervals from a list of the population

e.g Calling each person who is at the top of a page in a list of telephone numbers

Question 4

Stratified Sampling definition? Examples?

Answer 4

Stratified sampling is when you split the population into groups based on factors relevant to the research. Then you random sample from each group in proportion to the size of the group

e.g In a school of 400 pupils, 250 girls and 150 boys, taking a stratified sample of 80 pupils in which 50 would then be girls

Question 5

Quota Sampling definition? Examples?

Answer 5

Quota sampling is when you split the population into groups based on factors relevant to the research. The you opportunity sample from each group

e.g In a school of 400 pupils, 250 girls and 150 boys, taking an opportunity sample of 80 pupils that are not in a lesson that period

Question 6

Cluster Sampling definition? Examples?

Answer 6

Cluster sampling is when you first split the population into groups based on convenience and then randomly choose some clusters to study further

e.g Choosing five random countries and then finding the life expectancy of people in each of them

Question 7

What is an advantage and disadvantage of Simple Random sampling?

Answer 7

Advantage:
- Produces an unbiased sample

Disadvantage:
- Hard to do in practice
- Requires a list of the entire population and everybody to respond
- Is time consuming and expensive

Question 8

What is an advantage and disadvantage of Systematic Sampling?

Answer 8

Advantage:
- Avoids unwanted clustering of data
- Practically easier than using random number generators

Disadvantage:
- Requires a list of the entire population
- Is less random than simple random sampling as no longer independent

Question 9

What is an advantage and disadvantage of Stratified Sampling?

Answer 9

Advantage:
- Produces a sample representative over the factors identified

Disadvantage:
- Requires a list of the entire population, with additional information on each member
- Time consuming and expensive
- Determining which factors to consider is not always obvious

Question 10

What is an advantage and disadvantage of Cluster Sampling?

Answer 10

Advantage:
- Cheaper and Easier

Disadvantage:
- Less accurate than other methods - less representative

Question 11

What is an advantage and disadvantage of Opportunity Sampling?

Answer 11

Advantage:
- Cheap and convenient

Disadvantage:
- May not be generalisable across the whole population

Question 12

What is an advantage and disadvantage of Quota Sampling?

Answer 12

Advantage:
- Ensures the sample is representative over the factors identified

Disadvantage:
- May not be generalisable across the whole population

Question 13

What sampling methods are random?

Answer 13

• Simple random
• Systematic
• Stratified
• Cluster

Question 14

Which sampling methods are non-random?

Answer 14

• Quota
• Opportunity