A Level Maths Sampling Methods Flashcards
Random Sampling
Each thing in the sampling frame has an equal chance of being chosen, in order to avoid bias
Systematic Sampling
Required elements are chosen at regular intervals in an ordered list
Stratified Sampling
- Population divided into groups (strata)
- A simple random sample carried out in each group
Quota Sampling
- Divide population into groups according to characteristic of interest
- Determine size of each group in sample to reflect proportions within the population
- Actively choose people with each group via suitable means
- Until the quota of each group is filled
Opportunity Sampling
Find people at the same time the survey is being carried out
Advantages of a Census (2)
- gives a completely accurate result
- no bias
Disadvantages of a Census (4)
- time consuming
- expensive
- can’t be used when testing involves destruction
- large volume of data to process
Advantages of a Sample (3)
- cheaper
- quicker
- less data to process
Disadvantages of a Sample (2)
- data may not be accurate
- data may not be large enough to represent small sub groups
Advantages of Simple Random Sampling (3)
- bias free
- easy and cheap to implement
- each unit has equal chance of being chosen
Disadvantages of Simple Random Sampling (3)
- not suitable when population size is large
- may not be representative
- sampling frame needed
Advantages of Systematic Sampling (3)
- simple and quick to use
- suitable for large samples/populations
- no bias
Disadvantages of Systematic Sampling (2)
- sampling frame needed
- bias can be introduced if sampling frame not random
Advantages of Stratified Sampling (1)
- guarantees proportional representation of groups within population
Disadvantages of Stratified Sampling (3)
- population must be clearly classified into distinct strata
for selection within each strata: - may not be representative
- sampling frame needed
Advantages of Quota Sampling (4)
- allows small sample to be representative
- no sampling frame needed
- quick, easy, inexpensive
- allows for easy comparison between different groups
Disadvantages of Quota Sampling (3)
- can introduce bias
- population must be divided into groups
- can be costly or inaccurate
Advantages of Opportunity Sampling (2)
- easy to carry out
- inexpensive
Disadvantages of Opportunity Sampling (2)
- unlikely to provide a representative sample
- highly dependent on individual researcher
