Scientific Process - Sampling Techniques Flashcards
What is the target population?
Everyone that a researcher would like to sample
What is a sample?
A proportion of the population that a researcher would like to sample on to represent the whole population
What are the advantages of sampling?
Cheap
Fast
Can perform without a sampling frame
What are the advantages of using a whole population?
More accurate
What are the different types of sampling techniques?
Random sampling
Systematic sampling
Stratified sampling
Opportunity sampling
Volunteer sampling
How do you perform a simple random sample?
Give each item/participant a defining number and pick them from a hat or use a random number generator
What are the pros and cons of simple random sampling?
No bias - all random
Easy and cheap
Representative - can be generalised
Can’t use for large population size
Sampling frame needed
What is systematic sampling?
Choosing the item/participant at regular intervals
What are the pros and cons of systematic sampling?
Simple
Suitable for large samples
Sampling frame needed
Can be biased is sampling frame isn’t random - patterns in data
What is stratified sampling?
Population divided in different groups (strata) and you randomly choose the proportional amount of people randomly from each group
What are the pros and cons of stratified sampling?
Reflects population structure - can be representative
Guarantees proportional representation of groups in the population
Need sampling frame
Too much time needed to make groups
What is opportunity sampling?
Selecting participants who are readily available and willing to take part
What are the pros and cons of opportunity sampling?
Easiest and most practical method of getting large samples
No sampling frame needed
Can be biased or non representative
May have researcher bias
Not representative of whole population
What is volunteer sampling?
When people are self selected to take part in a study - usually adverts
What are the pros and cons of volunteer sampling?
Can be a useful way of finding specific people to take part in research
Only a certain type of people tend to volunteer for research - volunteer bias - unrepresentative
