Week 3 Flashcards
What us non-probability sample?
Sample is not random and chance of being selected cannot be estimated
What is probability sampling?
Designed to give an unbiased sample, where everyone has a chance of selection
What are the 4 main sampling techniques?
- Simple random
- Stratified random
- Cluster
- Systematic random
What us ‘ simple random sampling’?
Random selection of everyone in ‘population’ list.
Usually name in hat I’d random selection through database
What are the disadvantages of ‘simple random sample’?
Rarely done difficult to get population list
What is ‘stratified random sampling’?
Put in groups according to characteristics (gender) and are randomly selected.
What is ‘cluster’ sampling?
Random selections of large units (hospitals) which participants are then chooses from.
What us ‘systematic sampling’?
Random selection in intervals if every 10th person etc
What us attrition?
When people leave a study
What are the factoids effecting sample size?
Population
Design
Measurement
Practical
What is power calculation?
Calculation if sample size to adequately power the trail to detect the required differences in outcomes
What are the 3 common ways of randomising to trials?
Simple
Block
Stratified
What us meant by term ‘blinding’?
Concealment if allocation of group
What us meant by ‘single blind’?
One person (usually participant) knows which arm if the trail they are in, but the person assessing does not know.
What us meant by ‘double blind’?
Neither participant in assessor knows the arm
