Data collection Flashcards
(15 cards)
Describe how you would take a stratified sample
Divide the population into strata based on a characteristic
Take a simple random sample of each group
Same proportion sample in each strata
What are the advantages of stratified sampling?
Proportional representation of each group
Reflects population structure
What are the disadvantages of stratified sampling?
Population must be clearly classified
Sampling frame is needed
Not suitable when population is large
Describe how you would take a simple random sample
Each item has a number
Use a random number generator
Items with corresponding numbers become the sample
What are the advantages of simple random sampling
Bias free
Easy and cheap
Each number has an equal chance of being selected
What are the disadvantages of simple random sampling?
Not suitable when population is large
Sampling frame needed
Describe how you would take a systematic sample
Start at a random number between 1 and k
Take every kth element
What are the advantages of systematic sampling?
Simple and quick
Suitable for large samples/ populations
What are the disadvantages of systematic sampling?
Sampling frame needed
Can introduce bias if sample is not random
Describe how you would take an opportunity/ convenience sample
Sample taken from people available at time of study
What are the advantages of opportunity/ convenience sampling?
Easy
Inexpensive
What are the disadvantages of opportunity/ convenience sampling?
Unlikely to be representative
Highly dependent on individual researcher
Describe how you would take a quota sample
Population is divided by a characteristic
Quota is set by the interviewer to try and reflect the group
What are the advantages of quota sampling?
Quick and inexpensive
No sampling frame needed
Small sample size can still be representative
What are the disadvantages of quota sampling?
Can introduce bias
Groups can be inaccurate
Non-responses not recorded
