Sampling Flashcards
What is random sampling
Each possible ppt has equal chance of selection
What is systematic sampling
Every Nth person is pick from an in order population
What is stratified sampling
the sample reflects the makeup of the actual population (is proportionate.
What is opportunity sampling
Ppt selected from who is most easily available
What is volunteer sampling
Ppt put themselves forward for the study
How to do random sampling
Collect all names of ppt
put all names in a hat or generator
pull out names until sampling frame is complete
How to do systematic sampling
List the population an order (alphabetical)
assign all a number
pick every nth number
How to do stratified sampling
Identify sub groups in a population
calculate the required proportion of each subgroup
select random sample for each group with random
How to do opportunity sampling
Stand in convenient place
ask people who ‘fit the bill’ to partake in study
How to do volunteer sampling
Place poster in convenient place with contact details
first x amount to sign up are picked.
Volunteer strengths
Minimal effort fom researcher
Volunteer weaknesses
bias- particular type of person (curious excitable)
Opportunity strengths
Less effort from research
Opportunity weaknesses
Investigator bias
unrepresentative
Stratified strengths
No researcher bias,
Stratified weaknesses
Time consuming, cannot reflect individual differences
Systematic strengths
Free from researcher bias
Random strengths
free from researcher bias , representative to whole population
Random weaknesses
Time consuming and may be unwilling
Weakness of all sampling methods
Freak sample
