Sampling Flashcards
Simple random sampling pros and cons
- free of bias
- easy and cheap
- each unit has equal chance of selection
- not suitable when sample size is large
- sampling frame is needed
Systematic sampling pros and cons
- simple and quick
- suitable for large samples
- sampling frame needed
- can be biased if no sampling frame
Stratified sampling pros and cons
- accurately represent population proportion
- population must be clearly classified into distinct strata
Quota sampling pros and cons
- small sample can be representative
- no sampling frame needed
- easy and cheap
- biased
- must divided into groups which can be costly or invalid
Opportunistic sampling pros and cons
- easy
- cheap
- unlikely to be representative
- dependent on researcher
What does ‘tr’ mean in Daily Total Rainfall and what would one do with ‘tr’ entries to clean data set?
How would the estimate of mean be affected?
when rainfall < 0.05mm
Replace with 0.025 or 0.05
mean will be underestimated
What to do with tr values in rainfall samples?
Replace with 0 or 0.025
Mean would be underestimated
What is the sampling method that involves every individual in a population?
Census
What are the 3 types of random sampling?
Simple random
Systematic
Stratified
What are the 2 types of non-random sampling?
Opportunistic
Quota