3f- Sampling

Question 1

Where it is impractical to measure every individual in a population, what should be done?

Answer 1

A representative sample of the population is selected

Question 2

What determines the appropriate sample size of a population?

Answer 2

The extent of the natural variation within a population

Question 3

What kind of populations need a larger sample size?

Answer 3

More variable populations

Question 4

What should a representative sample share with the population as a whole?

Answer 4

The same mean and the same degree of variation about the mean

Question 5

What are the 3 types of sampling?

Answer 5

• random
• systematic
• stratified

Question 6

What happens in random sampling?

Answer 6

All members of the population have an equal chance of being selected

Question 7

What are some advantages and a disadvantage of random sampling?

Answer 7

Advantage- reduces the possibility of bias
- straight-forward process

Disadvantage- can result in poor representation of the overall population

Question 8

What happens in systematic sampling?

Answer 8

Members of a population are selected at regular intervals e.g. line transect

Question 9

What are an advantage and a disadvantage of systematic sampling?

Answer 9

Advantage- provides a more representative sample of the whole population

Disadvantage- sample may be biased as all members do not have an equal chance of being selected

Question 10

What happens in stratified sampling?

Answer 10

The population is organised into groups or “strata” according to a characteristic e.g. age. The number of individuals sampled is in proportion to the groups size in the main population

Question 11

What is an advantage and a disadvantage of stratified sampling?

Answer 11

Advantage- highly representative of the overall population

Disadvantage- setting up this technique requires the researcher to know the proportions of the group prior to beginning which isn’t always possible