Sampling Methods Flashcards
(13 cards)
1
Q
What is a simple random sample and how is it done?
A
- A sample of size n where each item has an equal chance of being selected
- Number each item in the sampling frame 1-n, use a random number generator to select random numbers
2
Q
What is systematic sampling?
A
The required items are chosen at regular intervals from an ordered list (e.g. every 3rd item)
3
Q
What is stratified sampling?
A
- The population is divided into mutually exclusive strata
- Simple random sample carried out in each group
- Amount sampled from each group reflects population structure
4
Q
What are the advantages of stratified sampling?
A
- Reflects population structure
- Guaranteed proportional representation
5
Q
What are the disadvantages of stratified sampling?
A
- Population must be clearly classified
- Disadvantages of random sampling in each strata
6
Q
A
7
Q
What are the advantages of a simple random sample?
A
- Free from bias
- Easy and cheap to implement
- Each number has an equal chance of being selected
8
Q
What are the disadvantages of a simple random sample?
A
- Not suitable for a large population
- A sampling frame is needed
9
Q
What are the advantages of systematic sampling?
A
- Easy and quick to use
- Suitable for large populations
10
Q
What are the disadvantages of systematic sampling?
A
- A sampling frame is needed
- Bias can be introduced is the sampling frame is not random
11
Q
What is quota sampling?
A
- Population is divided into strata to reflect the population structure
- A quote is set for each group and this many items are selected
- Items are selected non randomly
12
Q
What are the advantages of quota sampling?
A
- Small samples can still be reflective of the population
- No sampling frame required
- Easy, fast and cheap
13
Q
What is opportunity sampling?
A
Non-random sample taken from the items available that meet the criteria at the time of study
